Differential diagnosis — MCQs

Q: A female presents with a 1 × 1 cm thyroid swelling. What is the next best step in management?

TSH. ***Correct Option: TSH*** - **Thyroid-stimulating hormone (TSH)** is the most sensitive initial test to assess thyroid function when a thyroid nodule is discovered. - An abnormal TSH level (either high or low) can guide further investigation into whether the nodule is associated with a functional thyroid disorder. - **TSH should be the first test** according to American Thyroid Association guidelines for thyroid nodule evaluation. *Incorrect Option: I-131* - **I-131 (radioactive iodine therapy)** is a treatment modality for hyperthyroidism or thyroid cancer, not a diagnostic step for initial thyroid swelling evaluation. - Administering I-131 before assessing thyroid function would be inappropriate and could lead to unnecessary or harmful intervention. *Incorrect Option: TSH & T4* - While TSH is crucial, adding **T4 (thyroxine)** as an initial step is often not necessary if TSH is normal, as TSH alone effectively screens for primary thyroid dysfunction. - Measuring both TSH and T4 is typically reserved for situations where TSH is abnormal or when central hypothyroidism is suspected. *Incorrect Option: T3 & T4* - Measuring **T3 (triiodothyronine)** along with T4 as an initial screening for a thyroid nodule is generally not recommended. - T3 levels are primarily used to diagnose **hyperthyroidism** or to evaluate the severity of thyrotoxicosis after an abnormal TSH and T4 have been identified. *Incorrect Option: FNAC* - While **Fine Needle Aspiration Cytology (FNAC)** is an essential diagnostic tool for thyroid nodules, it is typically performed after TSH assessment. - FNAC is indicated for nodules >1 cm with suspicious ultrasound features, but **functional assessment with TSH comes first** to rule out hyperfunctioning nodules.

Q: A 70-year-old man is brought to the emergency department for the evaluation of worsening upper abdominal pain that he first noticed this morning after waking up. The pain is of tearing and burning quality and radiates to his back. Yesterday, he underwent an upper endoscopy and was diagnosed with gastritis and a large hiatal hernia. He has hypertension, hypercholesteremia, and a left bundle branch block that was diagnosed 5 years ago. The patient's mother died of myocardial infarction at the age of 70 years, and his father died of aortic dissection at the age of 65 years. The patient smoked one pack of cigarettes daily for the past 40 years, but quit 10 years ago. He drinks three beers daily. Current medications include hydrochlorothiazide, amlodipine, atorvastatin, and pantoprazole. The patient appears to be in mild distress. His temperature is 37.8°C (100.4°F), pulse is 103/min, and blood pressure is 135/89 mm Hg in the left arm and 132/90 mm Hg in the right arm. Cardiopulmonary examination shows crackling with every heartbeat. Abdominal examination shows tenderness to palpation in the epigastric region; bowel sounds are normal. Laboratory studies show: Hemoglobin 16.0 g/dL Leukocyte count 11,000/mm3 Na+ 140 mEq/L K+ 4.2 mEq/L Cl- 101 mEq/L HCO3- 25 mEq/L Creatinine 1.3 mg/dL Alanine aminotransferase 21 U/L Aspartate aminotransferase 43 U/L Lipase 40 U/L (N = 14–280) Troponin I 0.025 ng/mL (N < 0.1) Chest x-ray shows a large hiatal hernia and mediastinal lucency. A 12-lead EKG shows sinus tachycardia and a left bundle branch block. Which of the following is the most appropriate next step in diagnosis?

Contrast esophagography with gastrografin. ***Contrast esophagography with gastrografin*** - The patient's symptoms (worsening abdominal pain after endoscopy, tearing/burning quality radiating to the back) and imaging findings (mediastinal lucency on chest x-ray, crackling with every heartbeat suggestive of **Hamman's sign**) are highly indicative of **esophageal perforation**. - **Gastrografin** (water-soluble contrast) is the preferred initial study for suspected esophageal perforation because it is less irritating to the mediastinal tissues and can be reabsorbed if extravasated, unlike barium. *Contrast-enhanced CT of the aorta* - Although the patient has risk factors for **aortic dissection** (hypertension, family history), his symptoms are more classic for esophageal perforation, particularly after recent endoscopy. - The **mediastinal lucency** on chest x-ray strongly suggests esophageal perforation rather than aortic dissection. *Esophagogastroduodenoscopy* - Repeating an **EGD** would be contraindicated and dangerous in a patient with suspected esophageal perforation as it could worsen the tear and lead to further mediastinal contamination. - The initial EGD likely contributed to the current presumed perforation. *Abdominal ultrasound* - An abdominal ultrasound is useful for evaluating conditions like **cholecystitis**, **pancreatitis**, or abdominal aortic aneurysm, but it would not reliably detect an esophageal perforation. - The patient's pain radiation and chest x-ray findings point away from these diagnoses. *Coronary angiography* - While the patient has cardiac risk factors and a family history of **myocardial infarction**, his **troponin I** is normal, and his pain description of tearing/burning quality radiating to the back is less typical for cardiac ischemia. - The combined clinical picture and mediastinal lucency point strongly towards esophageal pathology.

Q: A 52-year-old woman comes to the emergency department because of a 3-hour history of right flank pain and nausea. Her only medication is a multivitamin. Her vital signs are within normal limits. Physical examination shows tenderness in the right costovertebral angle. Urinalysis shows a pH of 5.1, 50–60 RBC/hpf, and dumbbell-shaped crystals. Which of the following best describes the composition of the crystals seen on urinalysis?

Calcium oxalate. ***Calcium oxalate*** - The presence of **dumbbell-shaped crystals** in the context of **flank pain**, nausea, and **hematuria** is highly characteristic of calcium oxalate stones. - While calcium oxalate crystals can also be Envelope (octahedral) shaped, the **dumbbell shape** is a common morphology found, particularly in calcium oxalate monohydrate. *Calcium phosphate* - Calcium phosphate crystals typically present in an **alkaline urine** (pH > 7.0), appearing as amorphous, stellate, or platelike shapes, not dumbbell-shaped. - This patient's urine pH of 5.1 is **acidic**, making calcium phosphate less likely. *Magnesium ammonium phosphate* - Also known as **struvite crystals**, these are typically associated with **alkaline urine** and **urinary tract infections** caused by urea-splitting bacteria (e.g., *Proteus*). - They appear as **coffin-lid shaped crystals** and are not dumbbell-shaped. *Cystine* - Cystine crystals are associated with a rare genetic disorder, **cystinuria**, and appear as characteristic **hexagonal plates** in acidic urine. - They are not dumbbell-shaped. *Ammonium urate* - Ammonium urate crystals are typically observed in **alkaline urine** and have a characteristic **thorn apple** or spiky sphere appearance. - This patient's urine pH is acidic, and the crystal morphology doesn't match.

An 11-year-old boy is brought to the emergency department 30 minutes after he was found screaming and clutching his head. He has had nausea and occasional episodes of vomiting for 1 week, fever and left-sided headaches for 2 weeks, and increasing tooth pain over the past 3 weeks. He has no history of ear or sinus infections. He is in moderate distress. His temperature is 38.7°C (101.7°F), pulse is 170/min, respirations are 19/min, and blood pressure is 122/85 mmHg. He is confused and only oriented to person. The pupils react sluggishly to light. Fundoscopic examination shows papilledema bilaterally. Extraocular movements are normal. Flexion of the neck causes hip flexion. Which of the following is the most likely diagnosis?

A 70-year-old man is brought to the emergency department for the evaluation of worsening upper abdominal pain that he first noticed this morning after waking up. The pain is of tearing and burning quality and radiates to his back. Yesterday, he underwent an upper endoscopy and was diagnosed with gastritis and a large hiatal hernia. He has hypertension, hypercholesteremia, and a left bundle branch block that was diagnosed 5 years ago. The patient's mother died of myocardial infarction at the age of 70 years, and his father died of aortic dissection at the age of 65 years. The patient smoked one pack of cigarettes daily for the past 40 years, but quit 10 years ago. He drinks three beers daily. Current medications include hydrochlorothiazide, amlodipine, atorvastatin, and pantoprazole. The patient appears to be in mild distress. His temperature is 37.8°C (100.4°F), pulse is 103/min, and blood pressure is 135/89 mm Hg in the left arm and 132/90 mm Hg in the right arm. Cardiopulmonary examination shows crackling with every heartbeat. Abdominal examination shows tenderness to palpation in the epigastric region; bowel sounds are normal. Laboratory studies show: Hemoglobin 16.0 g/dL Leukocyte count 11,000/mm3 Na+ 140 mEq/L K+ 4.2 mEq/L Cl- 101 mEq/L HCO3- 25 mEq/L Creatinine 1.3 mg/dL Alanine aminotransferase 21 U/L Aspartate aminotransferase 43 U/L Lipase 40 U/L (N = 14–280) Troponin I 0.025 ng/mL (N < 0.1) Chest x-ray shows a large hiatal hernia and mediastinal lucency. A 12-lead EKG shows sinus tachycardia and a left bundle branch block. Which of the following is the most appropriate next step in diagnosis?

A 43-year-old woman was admitted to the hospital after a fall. When the emergency services arrived, she was unresponsive, did not open her eyes, but responded to painful stimuli. The witnesses say that she had convulsions lasting about 30 seconds when she lost consciousness after a traumatic event. On her way to the hospital, she regained consciousness. On admission, she complained of intense headaches and nausea. She opened her eyes spontaneously, was responsive but confused, and was able to follow motor commands. Her vital signs are as follows: blood pressure, 150/90 mm Hg; heart rate, 62/min; respiratory rate, 13/min; and temperature, 37.3℃ (99.1℉). There are no signs of a skull fracture. The pupils are round, equal, and poorly reactive to light. She is unable to fully abduct both eyes. Ophthalmoscopy does not show papillary edema or retinal hemorrhages. She has nuchal rigidity and a positive Kernig sign. An urgent head CT does not show any abnormalities. Which of the following is a proper investigation to perform in this patient?

A 52-year-old woman comes to the emergency department because of a 3-hour history of right flank pain and nausea. Her only medication is a multivitamin. Her vital signs are within normal limits. Physical examination shows tenderness in the right costovertebral angle. Urinalysis shows a pH of 5.1, 50–60 RBC/hpf, and dumbbell-shaped crystals. Which of the following best describes the composition of the crystals seen on urinalysis?

A 21-year-old college student is brought to the emergency department in a state of confusion. He also had one seizure approx. 45 minutes ago. He was complaining of fever and headache for the past 3 days. There was no history of nausea, vomiting, head trauma, sore throat, skin rash, or abdominal pain. Physical examination reveals: blood pressure 102/78 mm Hg, heart rate 122/min, and temperature 38.4°C (101.2°F). The patient is awake but confused and disoriented. He is sensitive to light and loud noises. Heart rate is elevated with a normal rhythm. Lungs are clear to auscultation bilaterally. The fundus examination is benign. Brudzinski’s sign is positive. What is the next best step in the management of this patient?

A 45-year-old woman undergoes endoscopic retrograde cholangiopancreatography (ERCP) for evaluation of suspected biliary strictures. The ERCP identifies 2 ducts in the pancreas (a small ventral duct and a larger dorsal duct). A diagnosis of a congenital pancreatic anomaly is made. Which of the following statements best describes this anomaly?

A 24-year-old female presents to her primary care physician with right knee pain for the last week. She states that she first noticed it after a long flight on her way back to the United States from Russia, where she had run a marathon along a mountain trail. The patient describes the pain as dull, aching, and localized to the front of her kneecap, and it worsens with sitting but improves with standing. Aspirin has not provided significant relief. The patient has a history of a torn anterior cruciate ligament (ACL) on the right side from a soccer injury three years ago. In addition, she was treated for gonorrhea last month after having intercourse with a new partner. At this visit, the patient’s temperature is 98.5°F (36.9°C), blood pressure is 112/63 mmHg, pulse is 75/min, and respirations are 14/min. Which of the following is most likely to establish the diagnosis?

Q10

A 48-year-old man with a history of nephrolithiasis presents with acute-onset left flank pain. He says that the pain started suddenly 4 hours ago and has progressively worsened. He describes the pain as severe, sharp, and localized to the left flank. The patient denies any fever, chills, nausea, vomiting, or dysuria. His past medical history is significant for nephrolithiasis diagnosed 4 years ago status post shockwave lithotripsy. The patient says, "I’m allergic to many pain medications, but there is one that I get all the time when I have this pain. I think it starts with D". He is afebrile and his vital signs are stable. On physical examination, he is writhing in pain and moaning. Exquisite left costovertebral angle tenderness is noted. Laboratory findings, including a urinalysis, are unremarkable. IV fluid resuscitation is administered. Which of the following is the best next step in the management of this patient?

Differential diagnosis US Medical PG Practice Questions and MCQs

Question 1: A female presents with a 1 × 1 cm thyroid swelling. What is the next best step in management?

A. I-131
B. TSH (Correct Answer)
C. TSH & T4
D. T3 & T4
E. FNAC

Explanation: ***Correct Option: TSH*** - **Thyroid-stimulating hormone (TSH)** is the most sensitive initial test to assess thyroid function when a thyroid nodule is discovered. - An abnormal TSH level (either high or low) can guide further investigation into whether the nodule is associated with a functional thyroid disorder. - **TSH should be the first test** according to American Thyroid Association guidelines for thyroid nodule evaluation. *Incorrect Option: I-131* - **I-131 (radioactive iodine therapy)** is a treatment modality for hyperthyroidism or thyroid cancer, not a diagnostic step for initial thyroid swelling evaluation. - Administering I-131 before assessing thyroid function would be inappropriate and could lead to unnecessary or harmful intervention. *Incorrect Option: TSH & T4* - While TSH is crucial, adding **T4 (thyroxine)** as an initial step is often not necessary if TSH is normal, as TSH alone effectively screens for primary thyroid dysfunction. - Measuring both TSH and T4 is typically reserved for situations where TSH is abnormal or when central hypothyroidism is suspected. *Incorrect Option: T3 & T4* - Measuring **T3 (triiodothyronine)** along with T4 as an initial screening for a thyroid nodule is generally not recommended. - T3 levels are primarily used to diagnose **hyperthyroidism** or to evaluate the severity of thyrotoxicosis after an abnormal TSH and T4 have been identified. *Incorrect Option: FNAC* - While **Fine Needle Aspiration Cytology (FNAC)** is an essential diagnostic tool for thyroid nodules, it is typically performed after TSH assessment. - FNAC is indicated for nodules >1 cm with suspicious ultrasound features, but **functional assessment with TSH comes first** to rule out hyperfunctioning nodules.

Question 2: What is the most appropriate initial investigation for a solitary thyroid nodule (STN)?

A. I-123 scan
B. Ultrasound (Correct Answer)
C. Fine-needle aspiration (FNA) biopsy
D. Thyroid function tests (TFTs)
E. CT scan of the neck

Explanation: ***Ultrasound*** - **Ultrasound** is the initial investigation of choice for a solitary thyroid nodule (STN) because it can differentiate between **solid, cystic, or mixed lesions**, assess nodule size, and identify suspicious features (e.g., microcalcifications, irregular margins, internal vascularity). - It also helps to determine if there are other nodules not palpable on physical examination, allowing for a more complete assessment of the **thyroid gland**. *Fine-needle aspiration (FNA) biopsy* - **FNA biopsy** is the most accurate diagnostic tool for evaluating the malignant potential of a thyroid nodule, but it is typically performed *after* an initial ultrasound has characterized the nodule. - It requires guidance (often by ultrasound) to obtain an adequate sample for cytological analysis, making ultrasound a prerequisite for optimal FNA performance. *Thyroid function tests (TFTs)* - **TFTs (TSH, T3, T4)** are important for assessing the functional status of the thyroid gland (e.g., hyperthyroidism or hypothyroidism) and can provide context for the nodule. - However, TFTs do not directly evaluate the **morphology or malignant potential** of the nodule itself, making them less appropriate as an initial, stand-alone investigation for an STN. *I-123 scan* - An **I-123 scan** (radioactive iodine uptake and scan) is used to determine if a nodule is "hot" (hyperfunctioning/benign) or "cold" (non-functioning/potentially malignant). - It is typically reserved for cases where **TSH levels are suppressed**, suggesting a hyperfunctioning nodule, and is not the first-line imaging modality for initial characterization of all STNs. *CT scan of the neck* - **CT scan** can visualize thyroid nodules and assess for extrathyroidal extension or lymphadenopathy, but it is **not recommended as an initial investigation** for STN. - It involves **radiation exposure**, is more expensive than ultrasound, and provides **less detailed characterization** of nodule morphology compared to ultrasound, making it a less appropriate first-line modality.

Question 3: An 11-year-old boy is brought to the emergency department 30 minutes after he was found screaming and clutching his head. He has had nausea and occasional episodes of vomiting for 1 week, fever and left-sided headaches for 2 weeks, and increasing tooth pain over the past 3 weeks. He has no history of ear or sinus infections. He is in moderate distress. His temperature is 38.7°C (101.7°F), pulse is 170/min, respirations are 19/min, and blood pressure is 122/85 mmHg. He is confused and only oriented to person. The pupils react sluggishly to light. Fundoscopic examination shows papilledema bilaterally. Extraocular movements are normal. Flexion of the neck causes hip flexion. Which of the following is the most likely diagnosis?

A. Subarachnoid hemorrhage
B. Cavernous sinus thrombosis
C. Pyogenic brain abscess (Correct Answer)
D. HSV encephalitis
E. Medulloblastoma

Explanation: ***Pyogenic brain abscess*** - The patient's history of **increasing tooth pain** over three weeks, followed by fever, headache, nausea, vomiting, confusion, and **papilledema**, strongly suggests a pyogenic brain abscess originating from a dental infection. - **Brudzinski's sign** (nuchal rigidity with **hip flexion upon neck flexion**) indicates meningeal irritation, and confusion with sluggish pupillary reaction are signs of increased intracranial pressure, consistent with an expanding mass lesion and inflammation. *Subarachnoid hemorrhage* - While it can cause sudden severe headache ("thunderclap"), nausea, vomiting, and meningeal signs, the **subacute onset** of symptoms (weeks) and the presence of prior dental pain make this diagnosis less likely. - **Fever** with prolonged, progressive symptoms and signs of focal neurological deficits (which can be subtle like confusion and sluggish pupils) are not typical for SAH. *Cavernous sinus thrombosis* - This condition is typically associated with infections in the facial region or sinuses, leading to **ophthalmoplegia**, **proptosis**, and chemosis due to involvement of cranial nerves III, IV, VI, and the ophthalmic/maxillary branches of V. - Although the patient has headache and fever, the absence of specific ocular signs like paralysis of extraocular muscles or proptosis makes this less probable. *HSV encephalitis* - While HSV encephalitis can cause fever, headache, altered mental status, and seizures, its onset is typically **acute to subacute** (days), and it often presents with **focal neurological deficits** or personality changes, not typically originating from dental pain. - The preceding tooth pain and the relatively prolonged symptom timeline (weeks) are less characteristic of primary HSV encephalitis. *Medulloblastoma* - This is a common posterior fossa tumor in children, which can cause symptoms of increased ICP like headache, nausea, vomiting, and papilledema due to hydrocephalus. - However, the presence of **fever** and a clear preceding **infectious source** (dental pain) points away from a primary tumor and more towards an infectious process like an abscess.

Question 4: A 70-year-old man is brought to the emergency department for the evaluation of worsening upper abdominal pain that he first noticed this morning after waking up. The pain is of tearing and burning quality and radiates to his back. Yesterday, he underwent an upper endoscopy and was diagnosed with gastritis and a large hiatal hernia. He has hypertension, hypercholesteremia, and a left bundle branch block that was diagnosed 5 years ago. The patient's mother died of myocardial infarction at the age of 70 years, and his father died of aortic dissection at the age of 65 years. The patient smoked one pack of cigarettes daily for the past 40 years, but quit 10 years ago. He drinks three beers daily. Current medications include hydrochlorothiazide, amlodipine, atorvastatin, and pantoprazole. The patient appears to be in mild distress. His temperature is 37.8°C (100.4°F), pulse is 103/min, and blood pressure is 135/89 mm Hg in the left arm and 132/90 mm Hg in the right arm. Cardiopulmonary examination shows crackling with every heartbeat. Abdominal examination shows tenderness to palpation in the epigastric region; bowel sounds are normal. Laboratory studies show: Hemoglobin 16.0 g/dL Leukocyte count 11,000/mm3 Na+ 140 mEq/L K+ 4.2 mEq/L Cl- 101 mEq/L HCO3- 25 mEq/L Creatinine 1.3 mg/dL Alanine aminotransferase 21 U/L Aspartate aminotransferase 43 U/L Lipase 40 U/L (N = 14–280) Troponin I 0.025 ng/mL (N < 0.1) Chest x-ray shows a large hiatal hernia and mediastinal lucency. A 12-lead EKG shows sinus tachycardia and a left bundle branch block. Which of the following is the most appropriate next step in diagnosis?

A. Contrast esophagography with gastrografin (Correct Answer)
B. Contrast-enhanced CT of the aorta
C. Esophagogastroduodenoscopy
D. Abdominal ultrasound
E. Coronary angiography

Explanation: ***Contrast esophagography with gastrografin*** - The patient's symptoms (worsening abdominal pain after endoscopy, tearing/burning quality radiating to the back) and imaging findings (mediastinal lucency on chest x-ray, crackling with every heartbeat suggestive of **Hamman's sign**) are highly indicative of **esophageal perforation**. - **Gastrografin** (water-soluble contrast) is the preferred initial study for suspected esophageal perforation because it is less irritating to the mediastinal tissues and can be reabsorbed if extravasated, unlike barium. *Contrast-enhanced CT of the aorta* - Although the patient has risk factors for **aortic dissection** (hypertension, family history), his symptoms are more classic for esophageal perforation, particularly after recent endoscopy. - The **mediastinal lucency** on chest x-ray strongly suggests esophageal perforation rather than aortic dissection. *Esophagogastroduodenoscopy* - Repeating an **EGD** would be contraindicated and dangerous in a patient with suspected esophageal perforation as it could worsen the tear and lead to further mediastinal contamination. - The initial EGD likely contributed to the current presumed perforation. *Abdominal ultrasound* - An abdominal ultrasound is useful for evaluating conditions like **cholecystitis**, **pancreatitis**, or abdominal aortic aneurysm, but it would not reliably detect an esophageal perforation. - The patient's pain radiation and chest x-ray findings point away from these diagnoses. *Coronary angiography* - While the patient has cardiac risk factors and a family history of **myocardial infarction**, his **troponin I** is normal, and his pain description of tearing/burning quality radiating to the back is less typical for cardiac ischemia. - The combined clinical picture and mediastinal lucency point strongly towards esophageal pathology.

Question 5: A 43-year-old woman was admitted to the hospital after a fall. When the emergency services arrived, she was unresponsive, did not open her eyes, but responded to painful stimuli. The witnesses say that she had convulsions lasting about 30 seconds when she lost consciousness after a traumatic event. On her way to the hospital, she regained consciousness. On admission, she complained of intense headaches and nausea. She opened her eyes spontaneously, was responsive but confused, and was able to follow motor commands. Her vital signs are as follows: blood pressure, 150/90 mm Hg; heart rate, 62/min; respiratory rate, 13/min; and temperature, 37.3℃ (99.1℉). There are no signs of a skull fracture. The pupils are round, equal, and poorly reactive to light. She is unable to fully abduct both eyes. Ophthalmoscopy does not show papillary edema or retinal hemorrhages. She has nuchal rigidity and a positive Kernig sign. An urgent head CT does not show any abnormalities. Which of the following is a proper investigation to perform in this patient?

A. Lumbar puncture (Correct Answer)
B. Angiography
C. Sonography
D. Brain MRI
E. EEG

Explanation: ***Lumbar puncture*** - The patient's symptoms, including **severe headache**, **nuchal rigidity**, **positive Kernig sign**, and **abnormal oculomotor findings** (poorly reactive pupils, inability to abduct eyes), despite a normal head CT, are highly suggestive of **subarachnoid hemorrhage**. A lumbar puncture is essential to look for **xanthochromia** (yellowish discoloration of CSF due to bilirubin from lysed red blood cells), which confirms the diagnosis, especially when CT is negative in the first 6-12 hours. - The history of a "traumatic event" followed by convulsions and transient loss of consciousness, along with a "lucid interval" then renewed symptoms (headache, confusion), raises suspicion for head injury leading to hemorrhagic event. The **elevated BP and bradycardia** (Cushing's reflex components), though not fully developed, also suggest increased intracranial pressure, further warranting investigation for hemorrhage. *Angiography* - While angiography (CTA or conventional) is performed **after a subarachnoid hemorrhage is confirmed** to identify the source of bleeding (e.g., aneurysm), it is not the *initial* diagnostic test to *confirm* the hemorrhage itself when CT is negative. - Doing an angiography before ruling out significant hemorrhage via LP (when CT is negative) is premature and could expose the patient to unnecessary risks without a confirmed diagnosis. *Sonography* - **Sonography** (ultrasound) has **no role** in the acute diagnosis of subarachnoid hemorrhage or other intracranial pathology in adults. - It is used for imaging the brain in neonates through the open fontanelles but is ineffective through the adult skull. *Brain MRI* - While an **MRI is more sensitive than CT for detecting subarachnoid hemorrhage** (especially subacute hemorrhage or small bleeds missed by CT), it is generally **less readily available** in an emergency setting than CT and LP. - In cases where CT is negative but clinical suspicion for SAH is high, **lumbar puncture is typically the next step** as it can detect early SAH via xanthochromia, which might not be immediately visible on MRI. MRI may be used later to identify causes or small bleeds not picked up by CT. *EEG* - An **EEG (electroencephalogram)** is used to **evaluate seizure activity** and other types of brain dysfunction related to electrical activity. - While the patient had convulsions, the primary concern given her overall presentation (severe headache, meningeal signs, altered mental status, and cranial nerve palsies) is **subarachnoid hemorrhage**, not solely seizure. An EEG would not help diagnose the underlying cause of her acute neurological deterioration.

Question 6: A 52-year-old woman comes to the emergency department because of a 3-hour history of right flank pain and nausea. Her only medication is a multivitamin. Her vital signs are within normal limits. Physical examination shows tenderness in the right costovertebral angle. Urinalysis shows a pH of 5.1, 50–60 RBC/hpf, and dumbbell-shaped crystals. Which of the following best describes the composition of the crystals seen on urinalysis?

A. Calcium phosphate
B. Magnesium ammonium phosphate
C. Cystine
D. Ammonium urate
E. Calcium oxalate (Correct Answer)

Explanation: ***Calcium oxalate*** - The presence of **dumbbell-shaped crystals** in the context of **flank pain**, nausea, and **hematuria** is highly characteristic of calcium oxalate stones. - While calcium oxalate crystals can also be Envelope (octahedral) shaped, the **dumbbell shape** is a common morphology found, particularly in calcium oxalate monohydrate. *Calcium phosphate* - Calcium phosphate crystals typically present in an **alkaline urine** (pH > 7.0), appearing as amorphous, stellate, or platelike shapes, not dumbbell-shaped. - This patient's urine pH of 5.1 is **acidic**, making calcium phosphate less likely. *Magnesium ammonium phosphate* - Also known as **struvite crystals**, these are typically associated with **alkaline urine** and **urinary tract infections** caused by urea-splitting bacteria (e.g., *Proteus*). - They appear as **coffin-lid shaped crystals** and are not dumbbell-shaped. *Cystine* - Cystine crystals are associated with a rare genetic disorder, **cystinuria**, and appear as characteristic **hexagonal plates** in acidic urine. - They are not dumbbell-shaped. *Ammonium urate* - Ammonium urate crystals are typically observed in **alkaline urine** and have a characteristic **thorn apple** or spiky sphere appearance. - This patient's urine pH is acidic, and the crystal morphology doesn't match.

Question 7: A 21-year-old college student is brought to the emergency department in a state of confusion. He also had one seizure approx. 45 minutes ago. He was complaining of fever and headache for the past 3 days. There was no history of nausea, vomiting, head trauma, sore throat, skin rash, or abdominal pain. Physical examination reveals: blood pressure 102/78 mm Hg, heart rate 122/min, and temperature 38.4°C (101.2°F). The patient is awake but confused and disoriented. He is sensitive to light and loud noises. Heart rate is elevated with a normal rhythm. Lungs are clear to auscultation bilaterally. The fundus examination is benign. Brudzinski’s sign is positive. What is the next best step in the management of this patient?

A. Intensive care unit referral
B. MRI of the brain
C. CT scan of the brain (Correct Answer)
D. Electroencephalography
E. Lumbar puncture

Explanation: ***CT scan of the brain*** - The patient presents with **altered mental status** (confusion, disorientation) and a **recent seizure**, which are **absolute indications for CT scan before lumbar puncture** according to IDSA guidelines. - Even with a benign fundus examination, CT is necessary to rule out **increased intracranial pressure**, **mass lesions**, or **brain abscess** that could cause herniation during LP. - In suspected meningitis with these risk factors, the standard approach is: **CT first → then LP if CT is safe** → empiric antibiotics if LP is delayed. - This protects against the potentially fatal complication of **cerebral herniation** during lumbar puncture. *Lumbar puncture* - While lumbar puncture is **essential for diagnosing meningitis** and analyzing CSF, it must be performed safely. - In patients with altered consciousness or seizures, **LP should be deferred until after CT** rules out contraindications. - If LP is delayed, **empiric antibiotics** (e.g., ceftriaxone + vancomycin + acyclovir) should be started immediately after blood cultures. *Intensive care unit referral* - ICU referral may be appropriate after initial diagnostic workup and stabilization, or if the patient deteriorates rapidly. - However, the **immediate next step** is to obtain neuroimaging before proceeding with LP to confirm the diagnosis. *MRI of the brain* - MRI provides superior detail for evaluating **encephalitis**, **brain abscess**, or other parenchymal pathology. - However, **CT is faster and more readily available** in the emergency setting and is sufficient for ruling out LP contraindications. - MRI may be obtained later for further characterization if needed. *Electroencephalography* - EEG evaluates seizure activity and can identify seizure foci or status epilepticus. - While the patient had a seizure, the **primary concern is suspected meningitis**, which requires CSF analysis (after safe neuroimaging). - EEG does not diagnose the underlying infectious cause and is not the immediate priority.

Question 8: A 45-year-old woman undergoes endoscopic retrograde cholangiopancreatography (ERCP) for evaluation of suspected biliary strictures. The ERCP identifies 2 ducts in the pancreas (a small ventral duct and a larger dorsal duct). A diagnosis of a congenital pancreatic anomaly is made. Which of the following statements best describes this anomaly?

A. Endoscopic ultrasonography reveals a 'stack sign' in patients with this condition
B. Patients with recurrent episodes of pancreatitis due to this condition do not require any intervention
C. It is the most common congenital anomaly of the pancreas
D. Magnetic resonance cholangiopancreatography (MRCP) scanning of the abdomen is the most sensitive non-invasive diagnostic technique for this condition (Correct Answer)
E. Most of the patients with this condition present in early childhood with abdominal symptoms

Explanation: ***Magnetic resonance cholangiopancreatography (MRCP) scanning of the abdomen is the most sensitive non-invasive diagnostic technique for this condition*** - **MRCP** is highly effective in visualizing the pancreatic ductal system, offering **non-invasive detection** of **pancreas divisum** by showing the separate dorsal and ventral ducts. - This imaging modality can clearly delineate the **anatomic variations**, including the anomalous drainage of the main pancreatic duct through the minor papilla. - MRCP is considered the **gold standard non-invasive imaging** for pancreas divisum, superior to CT or transabdominal ultrasound. *Endoscopic ultrasonography reveals a 'stack sign' in patients with this condition* - The "stack sign" is typically associated with **autoimmune pancreatitis**, characterized by a homogenous, hypoechoic enlargement of the pancreas, and is not a feature of congenital anomalies like pancreas divisum. - While EUS can visualize pancreatic ducts, it does not reveal a specific "stack sign" for pancreas divisum; the diagnosis relies on demonstrating separate ducts draining into different papillae. *Patients with recurrent episodes of pancreatitis due to this condition do not require any intervention* - Patients with **symptomatic pancreas divisum**, especially those with recurrent **pancreatitis**, often benefit from intervention such as **endoscopic sphincterotomy** of the minor papilla to improve drainage. - Leaving symptomatic cases untreated can lead to continued episodes of pancreatitis, causing progressive pancreatic damage and complications. *It is the most common congenital anomaly of the pancreas* - This statement is **factually true** - pancreas divisum affects 5-10% of the population and is indeed the most common congenital pancreatic anomaly. - However, in the context of this question asking what "**best describes** this anomaly," the statement about MRCP is more directly relevant as it describes the **diagnostic characteristics** rather than just epidemiological prevalence. - While this is an important fact about pancreas divisum, it is less specific in describing the anomaly itself compared to the diagnostic imaging features. *Most of the patients with this condition present in early childhood with abdominal symptoms* - The majority of individuals with **pancreas divisum** are **asymptomatic** throughout their lives (up to 95% remain asymptomatic). - When symptoms do occur, they typically manifest in **adulthood**, often as recurrent episodes of acute pancreatitis due to impaired drainage through the minor papilla.

Question 9: A 24-year-old female presents to her primary care physician with right knee pain for the last week. She states that she first noticed it after a long flight on her way back to the United States from Russia, where she had run a marathon along a mountain trail. The patient describes the pain as dull, aching, and localized to the front of her kneecap, and it worsens with sitting but improves with standing. Aspirin has not provided significant relief. The patient has a history of a torn anterior cruciate ligament (ACL) on the right side from a soccer injury three years ago. In addition, she was treated for gonorrhea last month after having intercourse with a new partner. At this visit, the patient’s temperature is 98.5°F (36.9°C), blood pressure is 112/63 mmHg, pulse is 75/min, and respirations are 14/min. Which of the following is most likely to establish the diagnosis?

A. Ballotable patella test
B. MRI of the knee
C. Anterior drawer test
D. Patellar compression with extended knee (Correct Answer)
E. Plain radiograph of the knee

Explanation: ***Patellar compression with extended knee*** - This maneuver helps to diagnose **patellofemoral pain syndrome** by compressing the patella against the femur, exacerbating symptoms if the articular cartilage is irritated. The patient's symptoms of **anterior knee pain** worsening with sitting and improving with standing, especially after intense physical activity (marathon) and a flight, are highly suggestive of patellofemoral pain syndrome ("runner's knee" or "airplane knee"). - The patient's history of a prior **ACL tear** may predispose her to patellofemoral pain due to altered knee biomechanics and muscle imbalances. *Ballotable patella test* - This test is used to detect significant **knee effusion**, but the patient's symptoms are not indicative of a large effusion, and this test would not specifically diagnose patellofemoral pain syndrome. - While some joint swelling can occur with patellofemoral pain, a ballotable patella suggests a more substantial fluid accumulation, which is not the primary symptom here. *MRI of the knee* - An MRI might show cartilage changes or other structural abnormalities but is generally not the initial diagnostic test for **patellofemoral pain syndrome**, which is primarily a clinical diagnosis. - Furthermore, MRI is an expensive imaging modality and is usually reserved for cases where other diagnoses are suspected or if conservative treatment fails. *Anterior drawer test* - This test assesses the integrity of the **anterior cruciate ligament (ACL)**. While the patient has a history of an ACL tear, her current symptoms are not consistent with acute ACL instability, but rather chronic anterior knee pain. - The anterior drawer test would be positive if there was an ongoing ACL tear or laxity, but it would not specifically diagnose patellofemoral pain syndrome. *Plain radiograph of the knee* - Plain radiographs are useful for identifying **bony abnormalities** like fractures, osteophytes, or severe arthritis, but they are typically normal in cases of patellofemoral pain syndrome. - They would not show the inflammation or cartilage irritation characteristic of patellofemoral pain, although they might rule out other bone-related causes of pain.

Question 10: A 48-year-old man with a history of nephrolithiasis presents with acute-onset left flank pain. He says that the pain started suddenly 4 hours ago and has progressively worsened. He describes the pain as severe, sharp, and localized to the left flank. The patient denies any fever, chills, nausea, vomiting, or dysuria. His past medical history is significant for nephrolithiasis diagnosed 4 years ago status post shockwave lithotripsy. The patient says, "I’m allergic to many pain medications, but there is one that I get all the time when I have this pain. I think it starts with D". He is afebrile and his vital signs are stable. On physical examination, he is writhing in pain and moaning. Exquisite left costovertebral angle tenderness is noted. Laboratory findings, including a urinalysis, are unremarkable. IV fluid resuscitation is administered. Which of the following is the best next step in the management of this patient?

A. Non-contrast CT of the abdomen and pelvis
B. Administer ibuprofen and acetaminophen for pain control (Correct Answer)
C. Administer dilaudid (hydromorphone) for pain control
D. Discharge patient with prescription of dilaudid with follow-up in 3 months
E. Admit to hospital floor for IV dilaudid patient-controlled analgesia

Explanation: ***Administer ibuprofen and acetaminophen for pain control*** - In acute renal colic with severe pain, **immediate pain management is the priority** before diagnostic imaging, especially in a hemodynamically stable patient without signs of infection or complications. - **NSAIDs (ibuprofen) are first-line therapy** per American Urological Association (AUA) and European Association of Urology (EAU) guidelines for acute renal colic, as they reduce pain and decrease ureteral spasm. - Acetaminophen provides additional analgesia through a different mechanism and is safe to combine with NSAIDs. - The patient's mention of "allergies to many pain medications" does not contraindicate a trial of NSAIDs and acetaminophen, which are generally well-tolerated. The reference to "D" medication is a distractor suggesting opioid-seeking behavior. - **Non-contrast CT will still be performed**, but after addressing the acute pain crisis - this is patient-centered, evidence-based care. *Non-contrast CT of the abdomen and pelvis* - While this is the **gold standard for diagnosing nephrolithiasis** and will be needed to confirm stone size, location, and complications, it is **not the immediate next step** in a patient writhing in severe pain. - The clinical presentation (acute flank pain, CVA tenderness, history of stones, normal UA, stable vitals) is classic for uncomplicated renal colic. - Modern clinical practice prioritizes **pain control first, then imaging** - delaying analgesia to obtain a CT first is not appropriate emergency management. - CT should be performed after initiating pain management to guide definitive treatment decisions. *Administer dilaudid (hydromorphone) for pain control* - While opioids like dilaudid can be used for renal colic, **NSAIDs are preferred first-line therapy** as they are equally or more effective for renal colic pain and have fewer side effects. - The patient's hint about "D" medication may suggest drug-seeking behavior, making it more appropriate to start with non-opioid analgesics. - Opioids should be reserved for cases where NSAIDs are contraindicated or ineffective after trial. *Discharge patient with prescription of dilaudid with follow-up in 3 months* - Discharging a patient with **severe, acute, undiagnosed pain** without imaging or confirmed diagnosis is unsafe and inappropriate. - The patient requires diagnostic imaging (CT) after pain control to assess stone burden, size, location, and likelihood of spontaneous passage. - Follow-up in 3 months is far too delayed - patients with acute renal colic need reassessment within days to weeks depending on stone characteristics. *Admit to hospital floor for IV dilaudid patient-controlled analgesia* - Admission is premature before attempting outpatient pain management and obtaining diagnostic imaging. - Most patients with uncomplicated renal colic can be managed in the emergency department with oral analgesics and discharged with close follow-up. - Admission criteria include: intractable pain/vomiting, suspected infection, acute kidney injury, solitary kidney, or stones unlikely to pass spontaneously. - Starting with PCA opioids bypasses appropriate first-line NSAID therapy.

Question 11: A 47-year-old male with a medical history significant for hypertension, recurrent urinary tract infections, mitral valve prolapse, and diverticulosis experiences a sudden, severe headache while watching television on his couch. He calls 911 and reports to paramedics that he feels as if "someone shot me in the back of my head." He is rushed to the emergency room. On exam, he shows no focal neurological deficits but has significant nuchal rigidity and photophobia. Of the options below, what is the most likely etiology of this man's headache?

A. Temporal Arteritis
B. Brain Tumor
C. Carotid Dissection
D. Migraine
E. Subarachnoid Hemorrhage (Correct Answer)

Explanation: ***Subarachnoid Hemorrhage*** - The sudden onset of a "thunderclap" headache, often described as the "worst headache of my life" or feeling like "someone shot me in the back of my head", is a classic presentation of **subarachnoid hemorrhage (SAH)**. - **Nuchal rigidity** (neck stiffness) and **photophobia** are common signs of meningeal irritation due to blood in the subarachnoid space. *Temporal Arteritis* - Typically presents in older individuals (usually >50 years old) with headache, **scalp tenderness**, jaw claudication, and visual disturbances, often associated with elevated inflammatory markers. - The sudden, extremely severe nature and the patient's age (47) make this less likely. *Brain Tumor* - Headache associated with a brain tumor usually has a more **gradual onset** and progressive worsening, often accompanied by **focal neurological deficits** or seizures. - The acute, severe "thunderclap" nature described here is not typical for a brain tumor headache. *Carotid Dissection* - Carotid dissection can cause a sudden headache, often unilateral, and may be associated with **neck pain**, neurological deficits (e.g., Horner's syndrome, transient ischemic attacks, stroke symptoms), or cranial nerve palsies. - While it can present with acute headache, the description of "worst headache of my life" and prominent nuchal rigidity without focal deficits points more strongly to SAH. *Migraine* - Migraines typically have a **prodrome** or a more gradual onset, often accompanied by aura, photophobia, phonophobia, and nausea; they are usually recurrent. - While migraines can be severe, the description of a sudden, explosive headache with associated nuchal rigidity is more characteristic of a serious underlying vascular event like SAH.

Question 12: A 23-year-old man presents to the emergency department with a severe headache. The patient states he gets sudden, severe pain over his face whenever anything touches it, including shaving or putting lotion on his skin. He describes the pain as electric and states it is only exacerbated by touch. He is currently pain free. His temperature is 98.1°F (36.7°C), blood pressure is 127/81 mmHg, pulse is 87/min, respirations are 15/min, and oxygen saturation is 98% on room air. Neurological exam is within normal limits, except severe pain is elicited with light palpation of the patient’s face. The patient is requesting morphine for his pain. Which of the following is the most likely diagnosis?

A. Tension headache
B. Migraine headache
C. Cluster headache
D. Trigeminal neuralgia (Correct Answer)
E. Malingering

Explanation: ***Trigeminal neuralgia*** - This patient's symptoms of **sudden, severe, electric-shock-like pain** in the face, triggered by light touch (e.g., shaving, lotion), are classic for **trigeminal neuralgia**. - The pain is typically unilateral, short-lasting, and occurs in the distribution of one or more branches of the **trigeminal nerve**. *Tension headache* - Tension headaches typically present as a **constant, dull aching** or pressure sensation, often described as a band around the head. - They are usually not associated with electric shock-like pain or specific triggers like light touch to the face. *Migraine headache* - Migraines are characterized by **throbbing, unilateral pain** often accompanied by **nausea, photophobia, and phonophobia**. - While severe, they do not typically present with the lancinating, trigger-point-induced pain pattern seen in this patient. *Cluster headache* - Cluster headaches are characterized by **severe, unilateral pain**, often orbital or periorbital, accompanied by **autonomic symptoms** (e.g., lacrimation, rhinorrhea, ptosis) on the affected side. - The pain is usually constant during an attack and is not described as electric shock-like or triggered by light touch, unlike trigeminal neuralgia. *Malingering* - While the patient is requesting morphine, his description of pain and its specific triggers are highly consistent with a recognized neurological condition, **trigeminal neuralgia**. - **Malingering** involves deliberately fabricating or exaggerating symptoms for external incentives, which is not supported by the classic presentation of a distinct medical condition.

Question 13: A 59-year-old woman comes to the emergency department 25 minutes after the onset of severe left periorbital pain and blurred vision in the same eye. The pain began soon after she entered a theater to watch a movie. She has a headache and vomited twice on the way to the hospital. Two weeks ago, she had acute sinusitis that resolved spontaneously. She has atrial fibrillation and hypertension. Current medications include metoprolol and warfarin. Her temperature is 37.1°C (98.8°F), pulse is 101/min, and blood pressure is 140/80 mm Hg. Visual acuity is counting fingers at 3 feet in the left eye and 20/20 in the right eye. The left eye shows conjunctival injection and edematous cornea. The left pupil is mid-dilated and irregular; it is not reactive to light. Extraocular movements are normal. Fundoscopic examination is inconclusive because of severe corneal edema. Which of the following is the most likely diagnosis?

A. Acute iridocyclitis
B. Angle-closure glaucoma (Correct Answer)
C. Retrobulbar neuritis
D. Central retinal artery occlusion
E. Open-angle glaucoma

Explanation: ***Angle-closure glaucoma*** - The sudden onset of **severe unilateral eye pain**, **blurred vision**, **nausea/vomiting**, and a **mid-dilated, fixed pupil** is highly characteristic of acute angle-closure glaucoma. - The context of entering a dark theater (causing pupillary dilation) and the finding of **conjunctival injection** and **corneal edema** further support this diagnosis. *Acute iridocyclitis* - While it can cause eye pain and conjunctival injection, it typically presents with a **small or constricted pupil** due to irritation, not a mid-dilated pupil. - Vision loss is usually less severe and gradual, and nausea/vomiting are less common unless pain is extreme. *Retrobulbar neuritis* - Characterized by **pain with eye movement** and **vision loss**, but does not typically present with conjunctival injection, corneal edema, or pupillary changes like a mid-dilated, fixed pupil. - Often associated with demyelinating diseases like multiple sclerosis. *Central retinal artery occlusion* - Causes **sudden, painless, monocular vision loss** (often described as "a curtain coming down") and a **cherry-red spot** on fundoscopy. - It does not usually cause severe eye pain, conjunctival injection, or pupillary abnormalities as described. *Open-angle glaucoma* - Involves **gradual, painless vision loss**, typically affecting peripheral vision first, and is usually asymptomatic until advanced stages. - It does not present with acute, severe pain, pupillary changes, or corneal edema.

Question 14: A 12-year-old boy is brought to the office by his mother with complaints of clear nasal discharge and cough for the past 2 weeks. The mother says that her son has pain during swallowing. Also, the boy often complains of headaches with a mild fever. Although his mother gave him some over-the-counter medication, there was only a slight improvement. Five days ago, his nasal discharge became purulent with an increase in the frequency of his cough. He has no relevant medical history. His vitals include: heart rate 95 bpm, respiratory rate 17/min, and temperature 37.9°C (100.2°F). On physical exploration, he has a hyperemic pharynx with purulent discharge on the posterior wall, halitosis, and nostrils with copious amounts of pus. Which of the following is the most likely cause?

A. Streptococcal pharyngitis
B. Common cold
C. Non-allergic vasomotor rhinitis
D. Diphtheria
E. Acute sinusitis (Correct Answer)

Explanation: ***Acute sinusitis*** - The progression from clear to **purulent nasal discharge** and cough, worsening over 5 days, along with **halitosis**, **facial pain** (implied by headache), and **purulent discharge on the posterior pharyngeal wall** (postnasal drip), are classic signs of acute bacterial sinusitis. - The persistence of symptoms for more than 10 days or worsening after 5-7 days of initial improvement (as seen here with the purulent discharge) strongly suggests a bacterial etiology rather than a viral infection. *Streptococcal pharyngitis* - While it causes **sore throat**, **fever**, and **hyperemic pharynx**, it typically presents with **tonsillar exudates** and **cervical lymphadenopathy**, not copious purulent nasal discharge or halitosis. - **Nasal discharge** is not a prominent feature of streptococcal pharyngitis; it's more characteristic of viral upper respiratory infections or sinusitis. *Common cold* - Usually resolves within 7-10 days, and while it starts with clear nasal discharge, it rarely progresses to **copious purulent discharge** and persistent fever for more than 5 days, indicating a bacterial superinfection. - The symptoms of **cough**, **sore throat**, and **headache** are general, but the severity and prolonged nature point away from a simple cold. *Non-allergic vasomotor rhinitis* - Characterized by **clear nasal discharge** and congestion triggered by environmental factors or temperature changes but does not involve **fever**, **purulent discharge**, **halitosis**, or **sore throat**. - It is a chronic condition and does not typically present with acute infectious symptoms or worsening over days. *Diphtheria* - A rare but severe infection characterized by a **tough, grayish membrane** covering the tonsils and pharynx, profound **sore throat**, **bull neck**, and signs of toxemia, which are not described in this case. - While it can cause pharyngitis, the absence of the characteristic membrane and the presence of copious purulent nasal discharge make it unlikely.

Question 15: A 31-year-old obese Caucasian female presents to the Emergency Department late in the evening for left lower quadrant pain that has progressively worsened over the last several hours. She describes the pain as sharp and shooting, coming and going. Her last bowel movement was this morning. She has also had dysuria and urgency. Her surgical history is notable for gastric bypass surgery 2 years prior and an appendectomy at age 9. She is sexually active with her boyfriend and uses condoms. Her temperature is 99.5 deg F (37.5 deg C), blood pressure is 151/83 mmHg, pulse is 86/min, respirations are 14/minute, BMI 32. On physical exam, she has left lower quadrant tenderness to palpation with pain radiating to the left groin and left flank tenderness on palpation. Her urinalysis shows 324 red blood cells/high power field. Her pregnancy test is negative. What is the next best step in management?

A. A KUB (kidneys, ureters and bladder) plain film
B. Noncontrast CT scan (Correct Answer)
C. Exploratory laparoscopy
D. Transvaginal ultrasound
E. Intravenous pyelogram

Explanation: ***Noncontrast CT scan*** - The patient presents with classic symptoms of **renal colic**, including acute onset, radiating flank and groin pain, dysuria, urgency, and significant hematuria (324 RBCs/HPF) on urinalysis, indicating a likely kidney stone. A **noncontrast CT scan** of the abdomen and pelvis is the most sensitive and specific imaging modality for detecting urinary tract calculi. - A noncontrast CT scan can readily identify the size, location, and number of stones, as well as detect complications such as **hydronephrosis**, which is crucial for determining the appropriate management strategy. *A KUB (kidneys, ureters and bladder) plain film* - While a KUB plain film can identify some radiopaque stones, it has **limited sensitivity and specificity** compared to CT, especially for radiolucent stones, small stones, or stones obscured by bowel gas. - **It does not provide information about hydronephrosis** or other renal pathologies, making it less useful for comprehensive evaluation of suspected kidney stones. *Exploratory laparoscopy* - This is an **invasive surgical procedure** that is not indicated as a primary diagnostic step for suspected kidney stones. - Exploratory laparoscopy would only be considered if imaging studies reveal an **acute abdominal emergency** requiring surgical intervention or if the diagnosis remained elusive after less invasive methods. *Transvaginal ultrasound* - A transvaginal ultrasound is primarily used to evaluate **pelvic reproductive organs** in females, such as the uterus and ovaries. - While it can sometimes visualize the distal ureters, it has **poor sensitivity for detecting ureteral stones** and is not the preferred imaging modality for kidney stone diagnosis. *Intravenous pyelogram* - An intravenous pyelogram (IVP) involves contrast administration and X-rays and was historically used for kidney stone diagnosis. However, it has been **largely replaced by noncontrast CT** due to its lower sensitivity, slower procedure time, and exposure to intravenous contrast and associated risks. - CT offers superior anatomical detail and can identify stones more accurately without the need for contrast in the setting of suspected renal colic.

Question 16: A 16-year-old girl is brought to the physician because of yellowish discoloration of her eyes and generalized fatigue since she returned from a 2-week class trip to Guatemala 2 days ago. During her time there, she had watery diarrhea, nausea, and lack of appetite for 3 days that resolved without treatment. She also took primaquine for malaria prophylaxis. Three weeks ago, she had a urinary tract infection that was treated with nitrofurantoin. Her immunizations are up-to-date. Her temperature is 37.1°C (98.8°F), pulse is 82/min and blood pressure is 110/74 mm Hg. Examination shows scleral icterus. There is no lymphadenopathy. The remainder of the examination shows no abnormalities. Laboratory studies show: Hemoglobin 12.1 g/dL Leukocyte count 6400/mm3 Platelet count 234,000/mm3 Reticulocyte count 1.1% Prothrombin time 12 sec (INR=1) Serum Bilirubin Total 2.8 mg/dL Direct 0.2 mg/dL Alkaline phosphatase 43 U/L AST 16 U/L ALT 17 U/L γ-Glutamyltransferase 38 U/L (N = 5–50) Anti-HAV IgG positive Anti-HBs positive A peripheral blood smear shows no abnormalities. Which of the following is the most likely diagnosis?

A. Crigler-Najjar syndrome
B. Rotor syndrome
C. Dubin-Johnson syndrome
D. Hepatitis B infection
E. Gilbert's syndrome (Correct Answer)

Explanation: ***Gilbert's syndrome*** - This patient presents with **unconjugated hyperbilirubinemia** (total bilirubin 2.8 mg/dL, direct 0.2 mg/dL), mild fatigue, and **scleral icterus**, which can be exacerbated by stressors like **fasting, dehydration, or illness** (the recent diarrheal illness). - The history of resolution of diarrhea and the normal liver enzymes (**ALT, AST, ALP, GGT**) rule out significant liver injury or cholestasis. The normal reticulocyte count and peripheral smear rule out hemolysis. *Crigler-Najjar syndrome* - This is a more severe genetic disorder of bilirubin conjugation, typically presenting with **profound unconjugated hyperbilirubinemia** and often leading to **kernicterus** in infancy or early childhood. - The patient's presentation at 16 years old with relatively mild symptoms makes Crigler-Najjar syndrome type I unlikely; type II is milder but still usually presents with higher unconjugated bilirubin levels than seen here. *Rotor syndrome* - This is a rare, benign autosomal recessive disorder characterized by **chronic, predominantly conjugated hyperbilirubinemia**. - The patient's bilirubin profile shows **unconjugated hyperbilirubinemia**, making Rotor syndrome an incorrect diagnosis. *Dubin-Johnson syndrome* - This is a benign, autosomal recessive disorder characterized by **chronic, predominantly conjugated hyperbilirubinemia** due to impaired hepatocellular excretion of bilirubin. - The patient's bilirubin profile shows **unconjugated hyperbilirubinemia**, which is not consistent with Dubin-Johnson syndrome. *Hepatitis B infection* - While viral hepatitis can cause jaundice and fatigue, it typically presents with **elevated transaminases (ALT, AST)**, indicating hepatocellular damage. This patient has normal liver enzymes. - The **anti-HBs positive result** indicates prior vaccination or resolved infection and immunity, not an active infection.

Question 17: A 52-year-old woman presents to the urgent care center with several hours of worsening abdominal discomfort that radiates to the back. The patient also complains of malaise, chills, nausea, and vomiting. Social history is notable for alcoholism. On physical exam, she is febrile to 39.5°C (103.1℉), and she is diffusely tender on abdominal palpation. Other vital signs include a blood pressure of 126/74 mm Hg, heart rate of 74/min, and respiratory rate of 14/min. Complete blood count is notable for 13,500 white blood cells (WBCs), and her complete metabolic panel shows bilirubin of 2.1 and amylase of 3210. Given the following options, what is the most likely diagnosis?

A. Choledocholithiasis
B. Cholelithiasis
C. Acute cholecystitis
D. Ascending cholangitis
E. Gallstone pancreatitis (Correct Answer)

Explanation: ***Gallstone pancreatitis*** - The elevated **amylase** (3210) strongly indicates **acute pancreatitis**, while the **elevated bilirubin** (2.1) suggests **biliary obstruction**, pointing toward a **gallstone etiology** blocking the common bile duct. - The radiating abdominal pain to the back, nausea, and vomiting along with systemic inflammatory response (fever, leukocytosis) are classic symptoms of **acute pancreatitis**. - While the patient has a history of alcoholism, the elevated bilirubin is the key finding that suggests **gallstone-induced** rather than alcoholic pancreatitis. *Choledocholithiasis* - While an elevated bilirubin suggests **biliary obstruction**, the significantly high **amylase** points primarily to **pancreatic inflammation** rather than just a stone in the common bile duct. - **Choledocholithiasis** typically causes **biliary colic**, jaundice, and potentially cholangitis, but not the markedly elevated amylase seen here unless it leads to pancreatitis. *Cholelithiasis* - **Cholelithiasis** (gallstones) often presents as **biliary colic**, characterized by episodic right upper quadrant pain, but usually without the systemic symptoms or markedly elevated amylase. - While it's a precursor to other biliary conditions, it doesn't explain the patient's severe generalized symptoms, fever, or the definitive **pancreatitis labs**. *Acute cholecystitis* - **Acute cholecystitis** involves inflammation of the **gallbladder**, typically causing **right upper quadrant pain**, fever, and leukocytosis, often with a positive Murphy's sign. - Although there's fever and leukocytosis, the **diffuse abdominal tenderness** and significantly high **amylase** are more indicative of pancreatitis than isolated gallbladder inflammation. *Ascending cholangitis* - **Ascending cholangitis** presents with **Charcot's triad** (fever, right upper quadrant pain, jaundice) or **Reynolds' pentad** (adding hypotension and altered mental status), but the key differentiating factor here is the extremely high amylase. - While **elevated bilirubin** suggests biliary involvement, the primary pathology indicated by the **amylase level** is pancreatic, not solely biliary infection.

Question 18: A 66-year-old man is transferred from another hospital after 3 days of progressively severe headache, vomiting, low-grade fever, and confusion. According to his partner, the patient has been dealing with some memory loss and complaining about headaches for the past 2 weeks. He has a history of interstitial pulmonary disease that required lung transplantation 2 years ago. Upon admission, he is found with a blood pressure of 160/100 mm Hg, a pulse of 58/min, a respiratory rate of 15/min, and a body temperature of 36°C (97°F). During the examination, he is found with oral thrush and symmetric and reactive pupils; there are no focal neurological signs or papilledema. A lumbar puncture is performed. Which of the following features would be expected to be found in this case?

A. Aspect: clear, opening pressure: normal, cell count: < 5 cells/µL, protein: normal, glucose: normal
B. Aspect: clear, opening pressure: normal, cell count: ↑ lymphocytes, protein: normal, glucose: normal
C. Aspect: cloudy, opening pressure: ↑, cell count: ↑ neutrophils, protein: ↑, glucose: ↓
D. Aspect: xanthochromic, opening pressure: normal, cell count: ↑ red blood cells, protein: normal, glucose: normal
E. Aspect: clear, opening pressure: ↑, cell count: ↑ lymphocytes, protein: ↑, glucose: ↓ (Correct Answer)

Explanation: ***Aspect: clear, opening pressure: ↑, cell count: ↑ lymphocytes, protein: ↑, glucose: ↓*** - This patient presents with symptoms highly suggestive of **cryptococcal meningitis**, a common opportunistic infection in immunocompromised individuals like transplant recipients. - **Cryptococcal meningitis** characteristically presents with **clear CSF** (not cloudy, which differentiates it from bacterial meningitis), **markedly elevated opening pressure** (often >25 cm H₂O), **lymphocytic pleocytosis**, **elevated protein**, and **decreased glucose** due to fungal metabolism. - The presence of **oral thrush** strongly suggests fungal infection in this immunocompromised patient. *Aspect: clear, opening pressure: normal, cell count: < 5 cells/µL, protein: normal, glucose: normal* - This describes **normal cerebrospinal fluid (CSF)** parameters, which would not be expected in a patient presenting with signs and symptoms of meningitis, such as headache, vomiting, fever, and confusion. - The patient's history of lung transplantation and oral thrush suggests an immunocompromised state and an opportunistic infection, ruling out normal CSF. *Aspect: clear, opening pressure: normal, cell count: ↑ lymphocytes, protein: normal, glucose: normal* - While **increased lymphocytes** can be seen in aseptic or viral meningitis, the overall picture of normal opening pressure, protein, and glucose does not fit this immunocompromised patient with subacute meningitis. - The presence of **oral thrush** and **2 weeks of symptoms** indicate a more severe opportunistic infection like cryptococcal meningitis, which would show elevated opening pressure and abnormal protein and glucose levels. *Aspect: cloudy, opening pressure: ↑, cell count: ↑ neutrophils, protein: ↑, glucose: ↓* - This CSF profile is characteristic of **bacterial meningitis**, which is primarily marked by **cloudy CSF** due to significant **neutrophilic pleocytosis**. - While the patient is immunocompromised, the history of **subacute symptoms** (2 weeks of headache/memory loss) and gradual deterioration is more typical of a fungal infection like **cryptococcal meningitis** rather than acute bacterial meningitis, which presents more acutely. *Aspect: xanthochromic, opening pressure: normal, cell count: ↑ red blood cells, protein: normal, glucose: normal* - **Xanthochromic CSF** with **elevated red blood cells** indicates subarachnoid hemorrhage. - While headache is present, the patient's symptoms of fever, progressive confusion, oral thrush, and immunocompromised status point away from a primary hemorrhagic event and towards an infectious etiology.

Question 19: A 19-year-old man with a past medical history significant only for moderate facial acne and mild asthma presents to his primary care physician with a new rash. He notes it has developed primarily over the backs of his elbows and is itchy. He also reports a 6-month history of foul-smelling diarrhea. He has no significant social or family history. The patient's blood pressure is 109/82 mm Hg, pulse is 66/min, respiratory rate is 16/min, and temperature is 36.7°C (98.0°F). Physical examination reveals crusting vesicular clusters on his elbows with a base of erythema and edema. What is the most likely underlying condition?

A. Type 2 diabetes mellitus
B. Celiac disease (Correct Answer)
C. Food allergy
D. IgA nephropathy
E. Hyperparathyroidism

Explanation: ***Celiac disease*** - The combination of **dermatitis herpetiformis** (pruritic, vesicular rash on extensor surfaces like elbows) and **malabsorption** symptoms (foul-smelling diarrhea) is highly suggestive of celiac disease. - Dermatitis herpetiformis is a chronic, intensely pruritic, **papulovesicular rash** that is considered the cutaneous manifestation of celiac disease, characterized by IgA deposition in the dermal papillae. *Type 2 diabetes mellitus* - While type 2 diabetes can present with various skin manifestations (e.g., **acanthosis nigricans**, necrobiosis lipoidica), these are typically not pruritic vesicular rashes on the elbows. - The patient's age and lack of typical risk factors for diabetes make it less likely, and foul-smelling diarrhea is not a primary symptom. *Food allergy* - Food allergies typically present with acute symptoms such as **urticaria**, angioedema, or anaphylaxis shortly after exposure to an allergen. - A chronic vesicular rash and persistent foul-smelling diarrhea are not characteristic presentations of a typical food allergy. *IgA nephropathy* - IgA nephropathy primarily affects the **kidneys**, presenting with hematuria and proteinuria, and does not cause a vesicular rash or malabsorptive diarrhea. - While it involves IgA deposition, it is in the glomeruli, not the skin or gut in the described manner. *Hyperparathyroidism* - Hyperparathyroidism is a disorder of calcium and phosphate metabolism, leading to symptoms like **bone pain**, kidney stones, and psychiatric symptoms. - It does not cause a pruritic vesicular rash or foul-smelling diarrhea.

Question 20: A 37‐year‐old woman presents with a severe, deep, sharp pain in her right hand and forearm. A week before she presented her pain symptoms, she fell on her right forearm and developed mild bruising. She has type-1 diabetes mellitus and is on an insulin treatment. The physical examination reveals that her right hand and forearm were warmer, more swollen, and had a more reddish appearance than the left side. She feels an intense pain upon light touching of her right hand and forearm. Her radial and brachial pulses are palpable. The neurological examination is otherwise normal. The laboratory test results are as follows: Hemoglobin 15.2 g/dL White blood cell count 6,700 cells/cm3 Platelets 300,000 cells/cm3 Alanine aminotransferase 32 units/L Aspartate aminotransferase 38 units/L C-reactive protein 0.4 mg/L Erythrocyte sedimentation rate 7 mm/1st hour The X-ray of the right hand and forearm do not show a fracture. The nerve conduction studies are also within normal limits. What is the most likely diagnosis?

A. Complex regional pain syndrome (Correct Answer)
B. Compartment syndrome
C. Diabetic neuropathy
D. Cellulitis
E. Limb ischemia

Explanation: ***Complex regional pain syndrome*** - This patient's symptoms of **severe pain**, **allodynia** (pain from light touch), **vasomotor changes** (warmth, swelling, redness), and **trophic changes** (initially normal X-ray) following a mild trauma align with the diagnosis of CRPS I. - The absence of significant inflammation markers (normal CRP, ESR), normal pulses, and normal neurological exam further supports CRPS over other inflammatory or ischemic conditions. *Compartment syndrome* - This condition is characterized by the **"6 Ps"** – pain, pallor, paresthesia, pulselessness, paralysis, and poikilothermia – resulting from increased pressure within a muscle compartment. - While pain is severe, the patient's **palpable pulses** and normal neurological exam make compartment syndrome less likely, as it typically involves significant neurological deficits and vascular compromise, often requiring urgent fasciotomy. *Diabetic neuropathy* - This condition typically presents as **bilateral, symmetrical pain** and sensory loss, often described as burning or tingling, primarily affecting the distal extremities (stocking-glove distribution). - The patient's **unilateral, acute onset of severe pain** and the presence of significant vasomotor changes do not fit the typical presentation of diabetic neuropathy. *Cellulitis* - Cellulitis is a **bacterial skin infection** characterized by localized redness, warmth, swelling, and pain, often with fever and elevated inflammatory markers. - The patient's **normal white blood cell count**, **normal CRP**, and **normal ESR** make an active infectious process like cellulitis highly unlikely. *Limb ischemia* - **Acute limb ischemia** typically presents with severe pain, pallor, paresthesia, pulselessness, and paralysis, due to a sudden lack of blood flow to the limb. - The patient's **palpable radial and brachial pulses** rule out significant large vessel obstruction, making limb ischemia an improbable diagnosis.

Question 21: A 25-year-old male presents to his primary doctor with difficulty sleeping. On exam, he is noted to have impaired upgaze bilaterally, although the rest of his ocular movements are intact. On pupillary exam, both pupils accommodate, but do not react to light. What is the most likely cause of his symptoms?

A. Melanoma with temporal lobe metastasis
B. Craniopharyngioma
C. Pinealoma (Correct Answer)
D. Spinal cord ependymoma
E. Frontal lobe cavernoma

Explanation: **Pinealoma** - The constellation of **impaired upgaze** (Parinaud syndrome) and **pupils that accommodate but do not react to light** (Argyll Robertson-like pupils) is highly suggestive of a lesion in the **dorsal midbrain**, a classic presentation of a **pinealoma**. - **Pinealomas** are tumors of the pineal gland, which is located in the dorsal midbrain area, leading to compression of surrounding structures. *Melanoma with temporal lobe metastasis* - **Temporal lobe metastases** typically cause symptoms related to the temporal lobe function, such as **seizures**, memory deficits, or language disturbances. - It would not specifically explain the characteristic ocular findings of **impaired upgaze** and **light-near dissociation** of the pupils. *Craniopharyngioma* - **Craniopharyngiomas** arise from Rathke's pouch and are typically located in the **suprasellar region**, often causing **visual field defects** (bitemporal hemianopsia) due to compression of the optic chiasm. - While they can cause hydrocephalus and other neurological symptoms, they are not the primary cause of the specific dorsal midbrain syndrome described. *Spinal cord ependymoma* - **Spinal cord ependymomas** are tumors of the spinal cord and would present with **spinal cord compression symptoms** like weakness, sensory loss, or bladder dysfunction. - These tumors do not affect the brainstem or ocular movements and therefore would not explain the patient's symptoms. *Frontal lobe cavernoma* - A **frontal lobe cavernoma** is a vascular malformation in the frontal lobe, most commonly presenting with **seizures** or focal neurological deficits related to the frontal lobe function (e.g., personality changes, motor weakness). - It would not cause the specific set of ocular findings observed in this patient, which point to a midbrain lesion.

Question 22: A 72-year-old man is brought into clinic by his daughter for increasing confusion. The daughter states that over the past 2 weeks, she has noticed that the patient “seems to stare off into space.” She reports he has multiple episodes a day during which he will walk into a room and forget why. She is also worried about his balance. She endorses that he has had several falls, the worst being 3 weeks ago when he tripped on the sidewalk getting the mail. The patient denies loss of consciousness, pre-syncope, chest pain, palpitations, urinary incontinence, or bowel incontinence. He complains of headache but denies dizziness. He reports nausea and a few episodes of non-bloody emesis but denies abdominal pain, constipation, or diarrhea. The patient’s medical history is significant for atrial fibrillation, diabetes, hypertension, hyperlipidemia, and osteoarthritis. He takes aspirin, warfarin, insulin, lisinopril, simvastatin, and ibuprofen. He drinks a half glass of whisky after dinner every night and smokes a cigar on the weekends. On physical examination, he is oriented to name and place but not to date. He is unable to spell "world" backward. When asked to remember 3 words, he recalls only 2. There are no motor or sensory deficits. Which of the following is the most likely diagnosis?

A. Ischemic stroke
B. Subdural hematoma (Correct Answer)
C. Vitamin B12 deficiency
D. Alzheimer disease
E. Normal pressure hydrocephalus

Explanation: ***Subdural hematoma*** - The patient's presentation with **gradual onset of confusion**, increasing forgetfulness, and **balance issues with falls** over a couple of weeks, especially after a fall three weeks prior, is highly suggestive of a subdural hematoma. - His use of **warfarin** and **aspirin** significantly increases his risk for bleeding, and the **headache and nausea/vomiting** are common symptoms of increased intracranial pressure. *Ischemic stroke* - An ischemic stroke typically presents with **acute, focal neurological deficits**, which are not described here. - While the patient has risk factors for stroke (atrial fibrillation, hypertension, diabetes), the **gradual onset** of symptoms over weeks makes it less likely. *Vitamin B12 deficiency* - Vitamin B12 deficiency can cause **cognitive impairment** and neurological symptoms, but it usually develops **insidiously over months to years**, not acutely over 2 weeks. - It is also associated with **peripheral neuropathy and megaloblastic anemia**, which are not reported. *Alzheimer disease* - Alzheimer's disease causes **progressive cognitive decline** over many years, starting with memory issues that gradually worsen. - The **relatively rapid 2-week progression** of symptoms and the clear precipitating factor of a fall make Alzheimer's less likely in this acute context. *Normal pressure hydrocephalus* - Normal pressure hydrocephalus (NPH) classically presents with a triad of **gait disturbance, urinary incontinence, and dementia**. - While the patient has gait issues and cognitive changes, the **absence of urinary incontinence** and the relatively rapid onset after a fall makes NPH less probable.

Question 23: An otherwise healthy 62-year-old woman comes to the physician because of a 3-year history of hearing loss. To test her hearing, the physician performs two tests. First, a vibrating tuning fork is held against the mastoid bone of the patient and then near her ear, to which the patient responds she hears the sound better on both sides when the tuning fork is held near her ear. Next, the physician holds the tuning fork against the bridge of her forehead, to which the patient responds she hears the sound better on the right side than the left. The patient's examination findings are most consistent with which of the following conditions?

A. Otosclerosis on the left
B. Cerumen impaction on the right
C. Cholesteatoma on the right
D. Acoustic neuroma on the left (Correct Answer)
E. Cochlear ischemia on the right

Explanation: ***Acoustic neuroma on the left*** - The patient's **Weber test lateralizing to the right** means sound is heard better on the right, indicating either a **sensorineural hearing loss on the left** or a conductive hearing loss on the right. - Her **Rinne test being positive bilaterally** (air conduction > bone conduction) rules out a conductive loss on the right, thus confirming unilateral **sensorineural hearing loss on the left side**. An acoustic neuroma is a common cause of progressive unilateral sensorineural hearing loss. *Otosclerosis on the left* - Otosclerosis typically causes a **conductive hearing loss** due to abnormal bone growth in the middle ear. - A conductive hearing loss on the left would result in the **Weber test lateralizing to the left**, not the right. *Cerumen impaction on the right* - Cerumen impaction causes **conductive hearing loss** in the affected ear. - If the right ear had a conductive loss, the **Weber test would lateralize to the right**, but the Rinne test in the right ear would show bone conduction > air conduction (negative Rinne), which is not the case here. *Cholesteatoma on the right* - A cholesteatoma typically causes **conductive hearing loss** by eroding ossicles or filling the middle ear space. - Similar to cerumen impaction, a conductive loss on the right would lead to a **negative Rinne test on the right**, which is not seen here as the Rinne test is positive bilaterally. *Cochlear ischemia on the right* - Cochlear ischemia would cause **sensorineural hearing loss** in the right ear. - If the right ear had a sensorineural loss, the **Weber test would lateralize to the left**, as the better (left) ear would perceive the sound more clearly, not the right.

Question 24: A 43-year-old man presents with acute-onset left flank pain for the past 6 hours. He describes the pain as severe, intermittent, colicky, and “coming in waves”, and he points to the area of the left costovertebral angle (CVA). He says he recently has been restricting oral liquid intake to only 2 glasses of water per day based on the advice of his healer. He also reports nausea and vomiting. The patient has a history of hypertension, gout, and type 2 diabetes mellitus. He is afebrile, and his vital signs are within normal limits. On physical examination, he is writhing in pain and moaning. There is exquisite left CVA tenderness. A urinalysis shows gross hematuria. Which of the following is the next best step in the management of this patient?

A. Non-contrast CT of the abdomen
B. Contrast CT of the abdomen and pelvis
C. Supine abdominal radiograph
D. Renal ultrasound
E. Non-contrast CT of the abdomen and pelvis (Correct Answer)

Explanation: **Non-contrast CT of the abdomen and pelvis** - **Non-contrast CT of the abdomen and pelvis** is the gold standard for diagnosing urolithiasis, providing high sensitivity and specificity for detecting stones, identifying their size and location, and assessing for hydronephrosis. - The patient's presentation with **acute-onset, severe, colicky flank pain**, nausea, vomiting, gross hematuria, and CVA tenderness is highly suggestive of **renal colic due to a kidney stone**. *Non-contrast CT of the abdomen* - This option is **insufficient** as kidney stones can be located in the ureters within the pelvis; a scan of the abdomen alone might miss stones in the distal ureter. - While a non-contrast CT is appropriate, the scope of only the abdomen is **incomplete** for evaluating the entire urinary tract that might be affected by stones. *Contrast CT of the abdomen and pelvis* - **Contrast-enhanced CT is generally not indicated** for the initial evaluation of suspected renal colic due to urolithiasis because it can obscure the visualization of urinary stones. - The use of contrast also carries risks such as **allergic reaction** and **contrast-induced nephropathy**, which are unnecessary in this acute, non-complicated setting. *Supine abdominal radiograph* - A supine abdominal radiograph (KUB) has **limited sensitivity** for detecting kidney stones, especially radiolucent stones (e.g., uric acid stones) or small stones. - It also provides **poor anatomical detail** and cannot assess for hydronephrosis or other complications as effectively as CT. *Renal ultrasound* - Renal ultrasound can detect **hydronephrosis** and some kidney stones but is less sensitive than CT for visualizing smaller stones, especially in the ureters. - Its diagnostic utility can be **limited by body habitus** and operator dependence, making it less reliable as a primary diagnostic tool for acute renal colic.

Question 25: A 55-year-old man presents to the emergency department for severe pain in his knee. The patient states that the pain began yesterday and has steadily worsened. The patient has a history of osteoarthritis of the knee, which was previously responsive to ibuprofen. He reports taking 3 doses of hydrochlorothiazide today after not taking his medication for 3 days. He recently attended a barbecue, which entailed eating beef and drinking alcohol. The patient was also recently treated for cellulitis. The patient has a past medical history of obesity, diabetes, and osteoarthritis. His temperature is 101°F (38.3°C), blood pressure is 157/98 mmHg, pulse is 95/min, respirations are 17/min, and oxygen saturation is 98% on room air. Physical exam is notable for a warm and erythematous left knee. There is tenderness to palpation of the left knee with limited range of motion due to pain. Which of the following is the best next step in management?

A. CT scan
B. Antibiotics
C. Naproxen
D. IV fluids
E. Arthrocentesis (Correct Answer)

Explanation: ***Arthrocentesis*** - The patient presents with a **monoarticular, acute, severely painful, warm, and erythematous knee joint**, which is highly suggestive of **septic arthritis or gout**. Both conditions require urgent diagnosis via **joint fluid analysis** obtained through arthrocentesis to guide treatment. - Arthrocentesis is crucial to differentiate between conditions like septic arthritis (requires immediate antibiotics) and gout (requires anti-inflammatory treatment), as their management strategies are vastly different. *CT scan* - A CT scan is generally not the initial diagnostic choice for acute monoarticular arthritis unless there is concern for a **fracture or complex intra-articular pathology**, which is not the primary differential here. - While it can help visualize bone and soft tissues, it does not provide the **definitive diagnosis** that joint fluid analysis offers for inflammatory or infectious arthritis. *Antibiotics* - While **septic arthritis** is a serious possibility given the presentation (fever, acute inflammation), empiric antibiotics should only be initiated *after* **arthrocentesis and joint fluid analysis** have been performed. - Administering antibiotics before obtaining joint fluid might **sterilize the joint fluid culture**, making it difficult to identify the causative organism and tailor appropriate therapy. *Naproxen* - **NSAIDs like naproxen** are a primary treatment for **gout**, which is a strong differential given the risk factors (recent meal/alcohol, diuretic use). - However, if the joint turns out to be **septically infected**, NSAIDs would not be sufficient and could potentially mask symptoms or delay appropriate treatment for a life-threatening condition. *IV fluids* - IV fluids might be considered if the patient showed signs of **dehydration or shock**, but his vital signs (apart from hypertension) and oxygen saturation are relatively stable. - While important for overall patient management, IV fluids do not address the **primary diagnostic or therapeutic needs** for acute monoarticular arthritis.

Question 26: A 63-year-old woman comes to the emergency department because of a 1-day history of progressive blurring and darkening of her vision in the right eye. Upon waking up in the morning, she suddenly started seeing multiple dark streaks. She has migraines and type 2 diabetes mellitus diagnosed at her last health maintenance examination 20 years ago. She has smoked one pack of cigarettes daily for 40 years. Her only medication is sumatriptan. Her vitals are within normal limits. Ophthalmologic examination shows visual acuity of 20/40 in the left eye and 20/100 in the right eye. The fundus is obscured and difficult to visualize on fundoscopic examination of the right eye. The red reflex is diminished on the right. Which of the following is the most likely diagnosis?

A. Vitreous hemorrhage (Correct Answer)
B. Migraine aura
C. Central retinal artery occlusion
D. Central retinal vein occlusion
E. Cataract

Explanation: ***Vitreous hemorrhage*** - Progressive blurring, darkening of vision, and "dark streaks" (floaters) with **diminished red reflex** and **obscured fundus** are classic signs of vitreous hemorrhage - The patient's history of **type 2 diabetes** and **smoking** increases the risk for **proliferative diabetic retinopathy**, a common cause of vitreous hemorrhage *Migraine aura* - Migraine aura typically involves **transient visual disturbances** such as shimmering lights, zigzags, or scotomas, often preceding a headache - Does not cause a **diminished red reflex** or **obscured fundus**, nor does it produce "dark streaks" that progress over a day *Central retinal artery occlusion* - Presents with **sudden, painless, severe vision loss** and a classic **"cherry-red spot"** on the macula with retinal whitening on fundoscopic exam - While vision is profoundly affected, the red reflex would typically be preserved, and the fundus would not be obscured by hemorrhage *Central retinal vein occlusion* - Characterized by **sudden, painless blurred vision** with diffuse retinal hemorrhages, venous engorgement, and cotton wool spots upon fundoscopic examination, often described as **"blood and thunder"** - Impairs vision but does not typically cause an **obscured fundus** or "dark streaks" in the same manner as vitreous hemorrhage *Cataract* - Causes **gradual, progressive painless vision loss** with glare, halos, and difficult night vision, typically over months to years - While it diminishes the red reflex, it would not present with acute onset of "dark streaks" or result in an acutely **obscured fundus** without other acute pathology

Question 27: A 32-year-old woman with a recurrent vesicular genital rash comes to the physician because of a 3-day history of a painful, pruritic rash that began on the extremities and has spread to her trunk. Her only medication is acyclovir. Her temperature is 38.1°C (100.6°F). Examination of the skin shows several reddish-purple papules and macules, some of which have a dusky center with a lighter ring around them. Which of the following is the most likely diagnosis?

A. Urticaria
B. Dermatitis herpetiformis
C. Eczema herpeticum
D. Stevens-Johnson syndrome
E. Erythema multiforme (Correct Answer)

Explanation: ***Erythema multiforme*** - The classic presentation of **target lesions** (reddish-purple papules and macules with a dusky center and lighter ring) starting on the extremities and spreading to the trunk is highly characteristic of erythema multiforme. - This condition is often triggered by infections, particularly **herpes simplex virus (HSV)**, making the patient's history of recurrent genital herpes a significant predisposing factor. *Urticaria* - Urticaria typically presents as **migratory, pruritic wheals** (hives) that are transient and blanchable, lacking the targetoid morphology described. - While pruritic, the lesions in urticaria do not have the distinct central dusky area or spreading pattern seen in erythema multiforme. *Dermatitis herpetiformis* - This condition is associated with **celiac disease** and presents with intensely pruritic, grouped vesicles and papules, predominantly on extensor surfaces like the elbows, knees, and buttocks. - The lesions are usually uniform in appearance, not targetoid, and the associated pruritus is often more severe than described. *Eczema herpeticum* - Eczema herpeticum occurs in individuals with pre-existing **atopic dermatitis** or other chronic skin conditions, where HSV infection leads to widespread crusted, punched-out erosions and vesicles. - While it involves HSV, the rash in this patient is not described as eczematous or having the characteristic "punched-out" lesions of eczema herpeticum. *Stevens-Johnson syndrome* - SJS is a severe mucocutaneous reaction often triggered by medications, characterized by widespread epidermal detachment, **mucosal involvement** (oral, ocular, genital), and atypical target lesions. - While SJS can have target-like lesions, they are often atypical and accompanied by widespread denudation and severe systemic symptoms, which are not fully described in this case, and the classic target lesions point more towards erythema multiforme.

Question 28: A 33-year-old woman comes to the physician because of vision impairment in her right eye for the past 2 weeks. During this period, she was unable to distinguish colors with her right eye. She also reports pain with eye movement. She has no double vision. She occasionally has headaches that are relieved by ibuprofen. One year ago, she had a similar episode that affected her left eye and resolved spontaneously. She has no history of serious illness. She works at a library and enjoys reading, even in poor lighting conditions. Her vital signs are within normal limits. The pupils are equal, round, and reactive to light and accommodation. Without correction, visual acuity is 20/50 in the left eye, and 20/100 in the right eye. With spectacles, the visual acuity is 20/20 in the left eye and 20/100 in the right eye. Slit lamp examination shows no abnormalities. A CT scan of the head shows no abnormalities. Which of the following is the most likely diagnosis?

A. Narrow-angle glaucoma
B. Retinal detachment
C. Macular degeneration
D. Retinitis pigmentosa
E. Optic neuritis (Correct Answer)

Explanation: ***Optic neuritis*** - This condition presents with **acute monocular vision loss**, **pain with eye movement**, and **dyschromatopsia** (inability to distinguish colors), which are classic symptoms of optic neuritis. - The recurrent nature affecting different eyes (**recurrent episodes in each eye**) and the spontaneous resolution are highly suggestive of **demyelinating disease**, such as **multiple sclerosis**, of which optic neuritis is often the initial presentation. *Narrow-angle glaucoma* - **Narrow-angle glaucoma** typically presents with **sudden, severe eye pain**, blurred vision, headache, and halos around lights due to acutely elevated intraocular pressure. - The examination would reveal a **mid-dilated pupil** and **conjunctival injection**, which are not described in this patient. *Retinal detachment* - Patients with **retinal detachment** usually report a sudden onset of **floaters**, **flashes of light**, and a **"curtain" or "shadow" obscuring part of their vision**. - **Pain with eye movement** and **dyschromatopsia** are not typical features of retinal detachment. *Macular degeneration* - **Macular degeneration** primarily affects central vision, causing **blurred or distorted vision**, particularly reading difficulty, and difficulty recognizing faces. - It usually presents in **older individuals** and is not characterized by pain with eye movement or sudden, recurrent episodes of vision loss with dyschromatopsia. *Retinitis pigmentosa* - **Retinitis pigmentosa** is a group of inherited eye diseases that cause progressive vision loss, beginning with **night blindness** and then gradual **peripheral vision loss** (tunnel vision). - The patient's acute monocular vision loss with pain and dyschromatopsia is not typical of the slow, progressive nature of retinitis pigmentosa.

Question 29: A 27-year-old young man presents to his primary care physician for weakness and tingling in his hand. The patient is an avid bodybuilder and has noticed that his grip strength has gradually worsened in both hands with symptoms worse at the end of a long workout. The patient has a past medical history of anabolic steroid use in high school. His current medications include a multivitamin, fish oil, and whey protein supplements. On physical exam, you note a muscular young man with male pattern hair loss. The patient has a loss of sensation bilaterally over the volar surface of the 4th and 5th digits and over the medial aspect of the dorsal hand. The patient has 3/5 grip strength of his left hand and 2/5 grip strength of his right hand. There is also notable weakness of finger adduction and abduction. The rest of the patient's physical exam is within normal limits. Which of the following is the most likely diagnosis?

A. Brachial plexopathy
B. Carpal tunnel syndrome
C. Cubital tunnel compression (Correct Answer)
D. Posterior interosseous nerve compression
E. Guyon's canal compression

Explanation: ***Cubital tunnel compression*** - This condition presents with **weakness** and **tingling** in the 4th and 5th digits and dorsal medial hand due to **ulnar nerve compression** at the elbow. - The patient's worsened symptoms with bodybuilding (repetitive elbow flexion), grip weakness, and weakness of finger adduction/abduction (interosseous muscles) are characteristic of **cubital tunnel syndrome**. - The sensory distribution includes both the volar 4th and 5th digits and the dorsal medial hand, consistent with ulnar nerve involvement proximal to the wrist. *Brachial plexopathy* - **Brachial plexopathy** would typically involve a broader distribution of sensory and motor deficits affecting multiple nerve roots or trunks, not isolated to the ulnar nerve distribution. - While it can cause weakness and sensory changes, the specific pattern of 4th and 5th digit involvement with interosseous weakness points more directly to **ulnar nerve compression**. *Carpal tunnel syndrome* - **Carpal tunnel syndrome** involves compression of the **median nerve** at the wrist, causing symptoms in the thumb, index, middle, and radial half of the ring finger. - The patient's symptoms are localized to the **ulnar nerve distribution** (4th and 5th digits plus dorsal medial hand), which is inconsistent with carpal tunnel syndrome. *Posterior interosseous nerve compression* - Compression of the **posterior interosseous nerve** (branch of the radial nerve) primarily causes **motor weakness** in the wrist and finger extensors, with no sensory deficits. - The patient's primary symptoms include significant **sensory loss** and weakness in the ulnar distribution, which does not align with posterior interosseous nerve involvement. *Guyon's canal compression* - While **Guyon's canal compression** affects the **ulnar nerve** at the wrist, it typically spares the **dorsal cutaneous branch of the ulnar nerve**, meaning sensation on the dorsal hand would be intact. - This patient has sensory loss on the **dorsal medial hand**, indicating compression proximal to where the dorsal cutaneous branch exits (approximately 5-6 cm proximal to the wrist), consistent with cubital tunnel syndrome rather than Guyon's canal.

Question 30: A 75-year-old female presents to your office with her daughter. The patient states that she feels perfectly well and that she does not know why she is present. The daughter states that over the last several years, the patient has become forgetful and recently forgot her grandchild's name, along with the groceries she was supposed to buy. She was also found lost 10 miles away from her house last week. The daughter also states that the patient has had urinary incontinence over the last few months and has been seeing little children in the morning that are not present. The patient denies any recent falls. Her vitals are normal and her physical exam does not reveal any focal neurological deficits. Her mini-mental status exam is scored 22/30. What is the most accurate test for this patient?

A. CT angiography of head
B. CT scan of head
C. Lumbar puncture
D. MRI scan of head (Correct Answer)
E. PET scan of head

Explanation: ***MRI scan of head*** - An MRI scan of the head is the **most accurate initial test** to evaluate cognitive decline and rule out structural/reversible causes of dementia. - This patient's presentation includes **progressive memory loss, disorientation, urinary incontinence, and visual hallucinations** - suggestive of **Lewy Body Dementia (LBD)** or potentially **Normal Pressure Hydrocephalus (NPH)**, though gait disturbance (a key NPH feature) is notably absent. - MRI provides detailed visualization of **brain atrophy patterns**, **ventricular enlargement** (for NPH), **white matter lesions** (vascular dementia), **hippocampal atrophy** (Alzheimer's), and excludes other reversible causes like **subdural hematoma, tumor, or stroke**. - **Must be performed first** before any invasive procedures like lumbar puncture. *CT scan of head* - A CT scan is useful for acute conditions like **hemorrhage, stroke, or mass lesions**, but it is **significantly less sensitive** than MRI for detecting subtle changes critical for dementia diagnosis. - Cannot adequately visualize **cortical atrophy, hippocampal volume loss, or subtle white matter changes** that help differentiate dementia subtypes. - While faster and more accessible, it is not the "most accurate" test for cognitive decline evaluation. *CT angiography of head* - CT angiography specifically visualizes **blood vessels** to detect **aneurysms, stenoses, or vascular malformations**. - While vascular disease can contribute to dementia, this test does not evaluate the **brain parenchyma** or structural changes necessary for diagnosing neurodegenerative conditions. - Not indicated as the initial test for cognitive impairment without focal vascular symptoms. *Lumbar puncture* - Lumbar puncture analyzes **cerebrospinal fluid (CSF)** for biomarkers (**amyloid-beta, tau, alpha-synuclein**), infection, or inflammation. - It is an **invasive procedure** that should only be performed **after neuroimaging** to rule out increased intracranial pressure, hydrocephalus, or mass lesions. - While useful for confirming specific dementia diagnoses (e.g., Alzheimer's or LBD biomarkers), it is a **second-line test**, not the initial most accurate diagnostic study. *PET scan of head* - PET imaging (FDG-PET or amyloid-PET) measures **metabolic activity** or **specific protein deposits** and is highly specific for certain dementias like **Alzheimer's disease** or **Frontotemporal dementia**. - It is typically a **specialized second-line test** used after structural imaging when the diagnosis remains unclear. - **More expensive and less available** than MRI, and not necessary as the initial most accurate test for broad cognitive impairment evaluation.

Question 31: A 7-year-old girl comes in to the emergency department with her mother for swelling of her left periorbital region. Yesterday morning she woke up with a painful, warm, soft lump on her left eyelid. Eye movement does not worsen the pain. Physical examination shows redness and swelling of the upper left eyelid, involving the hair follicles. Upon palpation, the swelling drains purulent fluid. Which of the following is the most likely diagnosis?

A. Xanthelasma
B. Chalazion
C. Dacryocystitis
D. Blepharitis
E. Hordeolum (Correct Answer)

Explanation: ***Hordeolum*** - A hordeolum (stye) is an **acute bacterial infection** of the sebaceous glands of the eyelid, often involving a hair follicle, presenting as a **painful, warm, soft lump with purulent drainage**. - The swelling of the eyelid **involving hair follicles** and the presence of **purulent fluid** are classic signs of a hordeolum. *Xanthelasma* - **Xanthelasma** consists of **yellowish plaques** on the eyelids, typically caused by cholesterol deposits, and is painless and not inflammatory. - It is a **chronic condition** and does not present with acute pain, warmth, or purulent discharge. *Chalazion* - A **chalazion** is a **painless, firm, non-tender nodule** resulting from a blocked meibomian gland, which is usually not painful or associated with acute inflammation and purulence. - Unlike a hordeolum, it is a **granulomatous reaction** and typically presents as a non-infectious, chronic lesion. *Dacryocystitis* - **Dacryocystitis** is an infection of the **lacrimal sac**, located at the inner corner of the eye, presenting with swelling, redness, and pain in that specific area. - This condition would not typically involve the eyelid's hair follicles or present with general eyelid purulence. *Blepharitis* - **Blepharitis** is a **chronic inflammation of the eyelid margins**, characterized by redness, flaking, and crusting of the eyelashes, often with itching or burning. - It causes **generalized eyelid discomfort and irritation**, but not a localized warm, painful, purulent lump like described in the scenario.

Question 32: A 64-year-old woman comes to the physician for a follow-up examination. She has had difficulty reading for the past 6 months. She tried using multiple over-the-counter glasses with different strengths, but they have not helped. She has hypertension and type 2 diabetes mellitus. Current medications include insulin and enalapril. Her temperature is 37.1°C (98.8°F), pulse is 80/min, and blood pressure is 126/84 mm Hg. The pupils are round and react sluggishly to light. Visual acuity in the left eye is 6/60 and in the right eye counting fingers at 6 feet. Fundoscopy shows pallor of the optic disc bilaterally. The cup-to-disk ratio is 0.7 in the left eye and 0.9 in the right eye (N = 0.3). Which of the following is the most likely diagnosis?

A. Open-angle glaucoma (Correct Answer)
B. Optic neuritis
C. Diabetic retinopathy
D. Age-related macular degeneration
E. Hypertensive retinopathy

Explanation: ***Open-angle glaucoma*** - The combination of **progressive vision loss**, **pallor of the optic disc**, and a significantly **increased cup-to-disk ratio** (0.7 and 0.9, normal <0.3) is highly characteristic of glaucoma. - The patient's **diabetes** and **hypertension** are risk factors for glaucoma, and the sluggish pupillary reaction can also be seen in advanced stages. *Optic neuritis* - Typically presents with **acute, painful vision loss** and often an **afferent pupillary defect** (Marcus Gunn pupil). - While it can cause optic disc pallor in chronic cases, the marked elevation of the cup-to-disk ratio is not a primary feature. *Diabetic retinopathy* - Characterized by microaneurysms, hemorrhages, exudates, and neovascularization on fundoscopy, not primarily **optic disc pallor** or an **increased cup-to-disk ratio**. - Visual changes are usually due to macular edema or tractional retinal detachment. *Age-related macular degeneration* - Primarily causes **central vision loss** and is characterized by drusen, pigmentary changes, or neovascularization in the macula. - It does not cause an **increased cup-to-disk ratio** or optic disc pallor. *Hypertensive retinopathy* - Features include **arteriolar narrowing**, AV nipping, flame hemorrhages, cotton wool spots, and papilledema (in severe cases), directly related to high blood pressure. - While it can affect the optic nerve, it usually doesn't lead to a sustained, progressive increase in the **cup-to-disk ratio** as the primary finding.

Question 33: A 25-year-old man presents to the emergency department with the sudden onset of neck pain and a severe spinning sensation for the last 6 hours. The symptoms initially began while he was lifting weights in the gym. He feels the room is spinning continuously, and he is unable to open his eyes or maintain his balance. The dizziness and pain are associated with nausea and vomiting. Past medical history is unremarkable. His blood pressure is 124/88 mm Hg, the heart rate is 84/min, the temperature is 37.0°C (98.6°F), the respiratory rate is 12/min, and the BMI is 21.6 kg/m2. On physical examination, he is awake and oriented to person, place, and time. Higher mental functions are intact. There are several horizontal beats of involuntary oscillatory eye movements on the left lateral gaze. He has difficulty performing repetitive pronation and supination movements on the left side. Electrocardiogram reveals normal sinus rhythm. Which of the following additional clinical features would you expect to be present?

A. Sensory aphasia
B. Past-pointing (Correct Answer)
C. Expressive aphasia
D. Hemiplegia
E. Bitemporal hemianopsia

Explanation: ***Past-pointing*** - The patient's symptoms (sudden onset of neck pain, severe spinning sensation, inability to maintain balance, horizontal nystagmus, and dysdiadochokinesia on the left) strongly suggest a posterior circulation stroke, likely involving the **cerebellum** or brainstem. - **Past-pointing**, a form of dysmetria, is a classic sign of cerebellar dysfunction, characterized by the inability to accurately touch a target due to issues with movement coordination and range. *Sensory aphasia* - **Sensory aphasia** (Wernicke's aphasia) is characterized by impaired comprehension and is typically associated with damage to the **left superior temporal gyrus** (Wernicke's area) in the dominant hemisphere. - The patient's higher mental functions are intact, making sensory aphasia an unlikely finding. *Expressive aphasia* - **Expressive aphasia** (Broca's aphasia) involves difficulty in speech production while comprehension remains relatively intact; it is usually linked to damage in the **left inferior frontal gyrus** (Broca's area). - Given the intact higher mental functions and the presentation of **posterior circulation symptoms**, expressive aphasia is not expected. *Hemiplegia* - **Hemiplegia** (paralysis of one side of the body) points to damage in the **contralateral motor cortex** or descending motor pathways, often from an anterior circulation stroke. - While vertebrobasilar stroke can sometimes cause motor deficits, the prominent symptoms here point to cerebellar and brainstem involvement rather than widespread motor cortex damage. *Bitemporal hemianopsia* - **Bitemporal hemianopsia** is a visual field defect characterized by loss of vision in the outer half of both visual fields, typically caused by compression of the **optic chiasm**, often by a pituitary tumor. - This condition is not associated with the acute onset of vertigo, neck pain, and cerebellar signs seen in this patient's presentation.

Question 34: A 37-year-old woman comes to the physician because of a 10-month history of excessive daytime sleepiness and fatigue. She says she has difficulty concentrating and has fallen asleep at work on numerous occasions. She also reports having frequent headaches during the day. She has no difficulty falling asleep at night, but wakes up gasping for breath at least once. She has always snored loudly and began using an oral device to decrease her snoring a year ago. She has occasional lower back pain, for which she takes tramadol tablets 1–2 times per week. She also began taking one rabeprazole tablet daily 3 weeks ago. She does not smoke. She is 175 cm (5 ft 7 in) tall and weighs 119 kg (262 lb); BMI is 38.8 kg/m2. Her vital signs are within normal limits. Physical and neurologic examinations show no other abnormalities. Arterial blood gas analysis on room air shows: pH 7.35 PCO2 51 mm Hg PO2 64 mm Hg HCO3- 29 mEq/L O2 saturation 92% An x-ray of the chest and ECG show no abnormalities. Which of the following is the most likely cause of this patient's condition?

A. Chronic inflammatory airflow limitation
B. Thickening of alveolar membranes
C. Drug-induced respiratory depression
D. Diurnal alveolar hypoventilation
E. Apneic episodes with obstructed upper airways (Correct Answer)

Explanation: **Apneic episodes with obstructed upper airways** - This patient has classic **obstructive sleep apnea (OSA)**, characterized by **loud snoring**, **waking up gasping for breath** (witnessed apneas), and **excessive daytime sleepiness**. - Her **obesity (BMI 38.8)** is a major risk factor for OSA, as excess soft tissue in the upper airway predisposes to collapse during sleep. - The ABG shows **compensated respiratory acidosis (pH 7.35, PCO2 51, HCO3- 29)** and **hypoxemia (PO2 64, O2 sat 92%)**, indicating chronic hypoventilation from recurrent apneic episodes. - OSA is the **underlying cause** of her condition; the oral device she uses is typically employed to treat OSA by repositioning the jaw to maintain airway patency. - The question asks for the **cause** of her condition, which is the **obstructed upper airways** leading to apneic episodes during sleep. *Diurnal alveolar hypoventilation* - While this patient does have daytime (diurnal) hypoventilation as evidenced by the elevated PCO2, this is a **consequence** of severe OSA, not the primary cause. - This describes **Obesity Hypoventilation Syndrome (OHS)**, which overlaps with OSA but refers specifically to the chronic hypoventilation state. - The **obstructed airways causing apneic episodes** are the underlying pathophysiology that leads to the chronic hypoventilation. *Chronic inflammatory airflow limitation* - This refers to **COPD**, which typically presents with **dyspnea, chronic cough, and wheezing**. - The patient is a **non-smoker**, has a **normal chest x-ray**, and lacks respiratory symptoms typical of COPD. - The clinical picture is classic for OSA, not obstructive lung disease. *Thickening of alveolar membranes* - This describes **interstitial lung diseases (ILD)**, which present with **progressive dyspnea, restrictive physiology**, and often **interstitial infiltrates on imaging**. - The patient's **normal chest x-ray** and lack of exertional dyspnea make ILD unlikely. - Her symptoms are related to sleep-disordered breathing, not parenchymal lung disease. *Drug-induced respiratory depression* - **Tramadol** (an opioid) can cause respiratory depression, but she takes it only **1-2 times per week** for back pain. - The ABG shows **compensated** respiratory acidosis with elevated bicarbonate, indicating a **chronic process** lasting weeks to months, not acute drug effect. - Her symptoms (snoring, gasping, daytime sleepiness) and obesity clearly point to OSA as the cause.

Question 35: A 24-year-old man presents to the emergency department after a motor vehicle accident. The patient was at a stop when he was rear-ended from behind by a vehicle traveling at 11 miles per hour. The patient complains of severe back pain but states he otherwise feels well. The patient is currently seeing a physical therapist who is giving him exercises to alleviate the back pain that is present every morning, relived by activity, and worse with inactivity. He is a student at the university and is struggling with his grades. His temperature is 98.4°F (36.9°C), blood pressure is 117/78 mmHg, pulse is 116/min, respirations are 12/min, and oxygen saturation is 99% on room air. Physical exam demonstrates a decreased range of motion of the patient's spine and tenderness to palpation over the vertebrae. The rest of the exam is deferred due to pain. The patient is requesting a note to excuse him from final exams and work. Which of the following is the most likely diagnosis in this patient?

A. Spondylolisthesis
B. Malingering
C. Herniated nucleus pulposus
D. Vertebral fracture
E. Musculoskeletal strain (Correct Answer)

Explanation: ***Musculoskeletal strain*** - The patient has a **pre-existing chronic back pain condition** (morning stiffness relieved by activity) that is being managed with physical therapy, suggesting a baseline musculoskeletal issue. - The **low-speed motor vehicle accident** (11 mph) is unlikely to cause significant structural injury and more likely represents an **acute-on-chronic exacerbation** of his underlying musculoskeletal condition. - While the chronic pattern (morning stiffness, improved with activity) raises consideration for inflammatory spondyloarthropathy, among the options provided, musculoskeletal strain best captures the **acute exacerbation of chronic mechanical back pain** in the context of minor trauma. - The patient's request for excuse from exams may represent legitimate need for rest or possible secondary gain, but does not change the primary musculoskeletal diagnosis. *Spondylolisthesis* - This involves **anterior slippage of one vertebra over another** and typically presents with mechanical back pain that worsens with **extension and activity** (not relieved by activity as in this patient). - There is no mention of the characteristic **step-off deformity** on palpation or radicular symptoms that often accompany symptomatic spondylolisthesis. - The patient's chronic pain pattern of improvement with activity argues against this diagnosis. *Malingering* - **Malingering** involves intentional fabrication or gross exaggeration of symptoms for external gain (avoiding exams/work). - However, this patient has **documented chronic back pain** with ongoing physical therapy, suggesting real underlying pathology rather than pure fabrication. - While secondary gain may be a factor, the presence of actual pre-existing symptoms and objective findings (decreased ROM, tenderness) makes pure malingering less likely. *Herniated nucleus pulposus* - A **herniated disc** typically presents with acute **radicular pain** radiating into the lower extremities, often with neurological deficits (weakness, numbness, reflex changes). - This patient's presentation is primarily **axial back pain** without mention of leg pain, paresthesias, or neurological deficits, making HNP unlikely. - The chronic nature and activity-related improvement pattern is atypical for acute disc herniation. *Vertebral fracture* - **Vertebral compression fractures** require either significant trauma or underlying bone pathology (osteoporosis, malignancy). - The **low-speed impact** (11 mph rear-end collision) in a young, otherwise healthy 24-year-old male is insufficient mechanism for vertebral fracture. - While there is tenderness over vertebrae, the patient's stable vital signs (aside from mild tachycardia likely from pain/anxiety) and absence of neurological compromise make acute fracture very unlikely.

Question 36: A 45-year-old man with a body mass index of 45 kg/m^2 presents to his primary care doctor with right hip pain. He asserts that the pain is instigated by walking up and down stairs around a construction site which he oversees. On physical exam, his hips are symmetric and equal with no tenderness to palpation bilaterally. His left lower extremity appears grossly normal with full range of motion. His right knee appears symmetric, but the patient whimpers when the anteromedial part of the tibial plateau is pressed. No other parts of his knee are tender. No tenderness is elicited with extension, flexion, varus, and valgus movements of the knee. McMurray's test is negative with both internal and external rotation of the right leg. What is the most likely diagnosis?

A. Patellar tendinitis
B. Prepatellar bursitis
C. Medial meniscus tear
D. Pes anserine bursitis (Correct Answer)
E. Lateral meniscus tear

Explanation: **Pes anserine bursitis** - The patient's presentation with **right hip pain (referred from the knee)**, exacerbated by climbing stairs and tenderness specifically over the **anteromedial tibial plateau**, is highly characteristic of pes anserine bursitis. The patient's **obesity (BMI 45 kg/m^2)** is a significant risk factor. - The **lack of tenderness** with other knee movements and a **negative McMurray's test** helps rule out meniscal tears. The pain is often described as hip pain due to radiation from the knee. *Patellar tendinitis* - This condition typically presents with localized pain and tenderness directly over the **patellar tendon**, just below the patella. - Pain is usually worsened by activities involving jumping or squatting, and not primarily by pressure on the anteromedial tibial plateau. *Prepatellar bursitis* - This involves inflammation of the bursa located directly **over the patella**, often due to direct trauma or prolonged kneeling. - The hallmark is **swelling and tenderness directly over the patella**, which is not described in this patient. *Medial meniscus tear* - While a medial meniscus tear can cause pain on the medial side of the knee, it is often associated with a **positive McMurray's test**, catching, locking, or giving way. - Tenderness would typically be along the **medial joint line**, and not specifically the more distal anteromedial tibial plateau where the pes anserinus bursa is located. *Lateral meniscus tear* - A lateral meniscus tear would cause pain and tenderness predominantly on the **lateral aspect of the knee**. - Similar to a medial meniscus tear, it is often associated with a **positive McMurray's test**, catching, or locking symptoms, none of which are present here.

Question 37: A 2-month-old boy is brought to the emergency room by his mother who reports he has appeared lethargic for the past 3 hours. She reports that she left the patient with a new nanny this morning, and he was behaving normally. When she got home in the afternoon, the patient seemed lethargic and would not breastfeed as usual. At birth, the child had an Apgar score of 8/9 and weighed 2.8 kg (6.1 lb). Growth has been in the 90th percentile, and the patient has been meeting all developmental milestones. There is no significant past medical history, and vaccinations are up-to-date. On physical examination, the patient does not seem arousable. Ophthalmologic examination shows retinal hemorrhages. Which of the following findings would most likely be expected on a noncontrast CT scan of the head?

A. Lens-shaped hematoma
B. Cortical atrophy
C. Crescent-shaped hematoma (Correct Answer)
D. Blood in the basal cisterns
E. Multiple cortical and subcortical infarcts

Explanation: ***Crescent-shaped hematoma*** - The clinical presentation with **lethargy**, a history of being with a **new caregiver**, and **retinal hemorrhages** strongly suggests **abusive head trauma** (shaken baby syndrome). - This typically results in a **subdural hematoma**, which appears as a **crescent-shaped collection of blood** on a noncontrast CT scan, reflecting bleeding into the potential space between the dura mater and arachnoid mater. *Lens-shaped hematoma* - A **lens-shaped (biconvex) hematoma** on CT is characteristic of an **epidural hematoma**, which typically results from a **skull fracture** tearing a meningeal artery. - While head trauma is present, the specific findings (retinal hemorrhages, lack of skull fracture mention, and mechanism of shaking) are more consistent with subdural rather than epidural bleeding. *Cortical atrophy* - **Cortical atrophy** refers to the shrinking of brain tissue and is typically seen in chronic conditions like **neurodegenerative diseases** or **long-standing severe malnutrition**. - It does not explain the acute onset of lethargy and retinal hemorrhages immediately following a potential traumatic event in an otherwise healthy infant. *Blood in the basal cisterns* - **Blood in the basal cisterns** is characteristic of **subarachnoid hemorrhage**, which can be caused by ruptured aneurysms (rare in infants), arteriovenous malformations, or severe trauma. - While abusive head trauma can sometimes cause subarachnoid bleeding, the primary finding in shaken baby syndrome is usually subdural hemorrhage, and retinal hemorrhages specifically point towards the shearing forces causing subdural bleeding. *Multiple cortical and subcortical infarcts* - **Multiple cortical and subcortical infarcts** indicate areas of brain tissue death due to **interrupted blood supply**, as seen in severe stroke or vasculitis. - This is not the primary or most likely finding in abusive head trauma, though severe head trauma can sometimes lead to secondary ischemic injury due to increased intracranial pressure or vascular disruption.

Question 38: A 72-year-old man is brought to the physician by his wife for memory issues over the last 7 months. The patient's wife feels that he has gradually become more forgetful. He commonly misplaces his car keys and forgets his children's names. He seems to have forgotten how to make dinner and sometimes serves uncooked noodles or raw meat. One night he parked his car in a neighbor's bushes and was found wandering the street. He has a history of hypertension, hyperlipidemia, and COPD. Current medications include atorvastatin, metoprolol, ipratropium, and fluticasone. Vital signs are within normal limits. He is alert and oriented to person and place only. Neurologic examination shows no focal findings. His Mini-Mental State Examination score is 19/30. A complete blood count and serum concentrations of electrolytes, urea nitrogen, creatinine, thyroid-stimulating hormone, liver function tests, vitamin B12 (cobalamin), and folate are within the reference range. Which of the following is the most appropriate next step in diagnosis?

A. Electroencephalography
B. PET scan
C. MRI of the brain (Correct Answer)
D. Lumbar puncture
E. Neuropsychologic testing

Explanation: ***MRI of the brain*** - An **MRI of the brain** is crucial for evaluating **structural causes of cognitive impairment**, such as tumors, strokes, hydrocephalus, or significant atrophy that might explain the patient's rapidly progressing memory loss and functional decline. - Given the patient's age, rapidly worsening dementia symptoms, and normal initial lab work, imaging is essential to rule out **reversible or treatable causes** and to characterize the extent of neurodegeneration. *Electroencephalography* - **EEG** is primarily used to detect **seizure activity** or to evaluate for rapidly progressive encephalopathies like Creutzfeldt-Jakob disease, which is not indicated by the patient's presentation. - The patient's symptoms are consistent with a dementia syndrome, not acute encephalopathy or seizures. *PET scan* - A **PET scan** (e.g., FDG-PET or amyloid-PET) can provide information about metabolic activity or amyloid plaques, useful for **differentiating types of dementia** (e.g., Alzheimer's disease). - However, it is an advanced test typically considered after structural imaging has ruled out other causes and when the diagnosis remains unclear. *Lumbar puncture* - **Lumbar puncture** is performed to analyze **cerebrospinal fluid (CSF)** for biomarkers (e.g., tau, Aβ42 levels) to help diagnose specific neurodegenerative diseases like Alzheimer's or to rule out infectious/inflammatory causes. - It's usually reserved for cases where other investigations are inconclusive or specific conditions are strongly suspected, and structural imaging has been performed. *Neuropsychologic testing* - **Neuropsychologic testing** provides a detailed assessment of various cognitive domains and can help to **characterize the pattern and severity of cognitive impairment**. - While valuable, it is usually performed after initial medical workup and structural imaging to understand the functional impact of any identified brain changes or to further delineate the type of cognitive disorder.

Question 39: A 27-year-old female presents to her primary care physician with a chief complaint of pain in her lower extremity. The patient states that the pain has gradually worsened over the past month. The patient states that her pain is worsened when she is training. The patient is a business student who does not have a significant past medical history and is currently not on any medications. She admits to having unprotected sex with multiple partners and can not recall her last menses. She drinks 7 to 10 shots of liquor on the weekends and smokes marijuana occasionally. She recently joined the cross country team and has been training for an upcoming meet. Her temperature is 99.5°F (37.5°C), pulse is 88/min, blood pressure is 100/70 mmHg, respirations are 10/min, and oxygen saturation is 97% on room air. On physical exam you note a very pale young woman in no current distress. Pain is localized to the lateral aspect of the knee and is reproduced upon palpation. Physical exam of the knee, hip, and ankle is otherwise within normal limits. The patient has 1+ reflexes and 2+ strength in all extremities. A test for STI's performed one week ago came back negative for infection. Which of the following is the most likely explanation for this patient's presentation?

A. Infection of the joint space
B. Friction with the lateral femoral epicondyle (Correct Answer)
C. Cartilaginous degeneration from overuse
D. Meniscal tear
E. Cartilaginous degeneration from autoimmunity

Explanation: ***Friction with the lateral femoral epicondyle*** - The patient's presentation of **lateral knee pain**, worsening with activity (cross-country training), and localized tenderness suggests **iliotibial band syndrome (ITBS)**. - ITBS results from repetitive friction of the **iliotibial band** over the **lateral femoral epicondyle** during knee flexion and extension, common in runners. *Infection of the joint space* - While the patient has a low-grade fever, there are no other signs of **septic arthritis**, such as **swelling**, **warmth**, **erythema**, or significant pain at rest. - Furthermore, a recent STI test was negative, and the pain is localized to the lateral aspect, not primarily within the joint. *Cartilaginous degeneration from autoimmunity* - There are no symptoms or signs to suggest an **autoimmune condition**, such as **morning stiffness**, **symmetrical joint involvement**, or other systemic symptoms. - The pain is localized and activity-related, not typical of autoimmune arthritis. *Cartilaginous degeneration from overuse* - **Cartilaginous degeneration (osteoarthritis)** due to overuse is less likely in a 27-year-old without a history of significant trauma or predisposing factors. - While overuse contributes to ITBS, direct cartilaginous degeneration typically presents with more diffuse pain or crepitus within the joint. *Meniscal tear* - A **meniscal tear** would typically cause **mechanical symptoms** like **clicking**, **locking**, or **catching** of the knee, which are not described. - Pain from a meniscal tear is generally localized to the **joint line** (medial or lateral) and not specifically to the lateral femoral epicondyle.

Question 40: A 45-year-old woman comes to the emergency department because of right upper abdominal pain and nausea that have become progressively worse since eating a large meal 8 hours ago. She has had intermittent pain similar to this before, but it has never lasted this long. She has a history of hypertension and type 2 diabetes mellitus. She does not smoke or drink alcohol. Current medications include metformin and enalapril. Her temperature is 38.5°C (101.3°F), pulse is 90/min, and blood pressure is 130/80 mm Hg. The abdomen is soft, and bowel sounds are normal. The patient has sudden inspiratory arrest during right upper quadrant palpation. Laboratory studies show a leukocyte count of 13,000/mm3. Serum alkaline phosphatase, total bilirubin, amylase, and aspartate aminotransferase levels are within the reference ranges. Imaging is most likely to show which of the following findings?

A. Dilated common bile duct with intrahepatic biliary dilatation
B. Enlargement of the pancreas with peripancreatic fluid
C. Gallstone in the cystic duct (Correct Answer)
D. Gas in the gallbladder wall
E. Decreased echogenicity of the liver

Explanation: ***Gallstone in the cystic duct*** - The patient's presentation with **right upper quadrant pain** after a fatty meal, **nausea**, **fever**, **leukocytosis**, and a positive **Murphy's sign** (inspiratory arrest during palpation) is highly suggestive of **acute cholecystitis**. - **Acute cholecystitis** is most commonly caused by an obstructing gallstone in the **cystic duct**, leading to inflammation of the gallbladder. *Dilated common bile duct with intrahepatic biliary dilatation* - This finding suggests **choledocholithiasis** (gallstone in the common bile duct) or another obstruction of the common bile duct, which would typically cause **elevated bilirubin** and **alkaline phosphatase**. - These laboratory values are **within normal limits** for this patient, making choledocholithiasis less likely. *Enlargement of the pancreas with peripancreatic fluid* - These findings are characteristic of **acute pancreatitis**, which would present with elevated **amylase** and **lipase**. - The patient's **amylase level is normal**, ruling out acute pancreatitis as the primary diagnosis. *Gas in the gallbladder wall* - This indicates **emphysematous cholecystitis**, a severe form of acute cholecystitis typically seen in elderly or immunocompromised patients, often with diabetes. - While the patient has diabetes, the overall clinical picture does not specifically point to this more advanced and rare complication, and it's not the *most likely* initial finding for typical acute cholecystitis. *Decreased echogenicity of the liver* - Decreased echogenicity of the liver is typically associated with conditions like **fatty liver disease** or **hepatitis**. - While the patient has risk factors for fatty liver (type 2 diabetes), this finding does not explain her acute symptoms of right upper quadrant pain, fever, and Murphy's sign, which point towards gallbladder pathology.

Question 41: A 51-year-old homeless man presents to the emergency department with severe abdominal pain and cramping for the past 3 hours. He endorses radiation to his back. He adds that he vomited multiple times. He admits having been hospitalized repeatedly for alcohol intoxication and abdominal pain. His temperature is 103.8° F (39.8° C), respiratory rate is 15/min, pulse is 107/min, and blood pressure is 100/80 mm Hg. He refuses a physical examination due to severe pain. Blood work reveals the following: Serum: Albumin: 3.2 gm/dL Alkaline phosphatase: 150 U/L Alanine aminotransferase: 76 U/L Aspartate aminotransferase: 155 U/L Gamma-glutamyl transpeptidase: 202 U/L Lipase: 800 U/L What is the most likely diagnosis of this patient?

A. Duodenal peptic ulcer
B. Choledocholithiasis
C. Pancreatitis (Correct Answer)
D. Cholecystitis
E. Gallbladder cancer

Explanation: ***Pancreatitis*** - The patient's history of **repeated alcohol intoxication** and abdominal pain, combined with **severe abdominal pain radiating to the back**, vomiting, and significantly elevated **lipase (800 U/L)**, are highly indicative of **acute pancreatitis**. - The elevated **liver enzymes (ALT, AST, GGT)** and **alkaline phosphatase** can be associated with cholestasis or liver involvement often seen in alcohol-induced pancreatitis or can be elevated due to a gallstone lodged in the common bile duct, which is also a common cause of pancreatitis. *Duodenal peptic ulcer* - While duodenal ulcers cause severe abdominal pain, they typically present with **epigastric pain** that may be relieved by food, and often cause **melena or hematemesis** if bleeding. - The extremely high **lipase level** and pain radiating to the back are not characteristic of an uncomplicated duodenal ulcer. *Choledocholithiasis* - **Choledocholithiasis** (gallstones in the common bile duct) can cause severe right upper quadrant or epigastric pain and elevated liver enzymes, but it doesn't typically present with an isolated, dramatically high **lipase** level without concomitant pancreatitis. - The main symptom is **biliary colic**, often post-prandial, and usually involves jaundice or cholangitis if infected. *Cholecystitis* - **Cholecystitis** presents with **right upper quadrant pain**, often radiating to the shoulder, associated with fever and nausea, and is usually triggered by fatty meals. - Although there might be some elevation in liver enzymes and amylase/lipase, the **markedly elevated lipase** and pain radiating to the back are more suggestive of pancreatitis. *Gallbladder cancer* - **Gallbladder cancer** typically presents with more insidious symptoms, such as chronic right upper quadrant pain, weight loss, jaundice, and anorexia. - It would not usually present with an acute episode of **severe abdominal pain and drastically high lipase** in this manner.

Question 42: A previously healthy 18-year-old woman comes to the physician because of a 2-day history of swelling and itchiness of her mouth and lips. It decreases when she eats cold foods such as frozen fruit. Four days ago, she underwent orthodontic wire-placement on her upper and lower teeth. Since then, she has been taking ibuprofen twice daily for the pain. For the past 6 months, she has been on a strict vegan diet. She is sexually active with one partner and uses condoms consistently. She had chickenpox that resolved spontaneously when she was 6 years old. Her vitals are within normal limits. Examination shows diffuse erythema and edema of the buccal mucosa with multiple serous vesicles and shallow ulcers. Stroking the skin with pressure does not cause blistering of the skin. The remainder of the examination shows no abnormalities. Which of the following is the most likely cause of these symptoms?

A. Vitamin deficiency
B. Dermatitis herpetiformis
C. Allergic contact dermatitis (Correct Answer)
D. Reactivation of varicella zoster virus
E. Herpes labialis

Explanation: ***Allergic contact dermatitis*** - The symptoms of **swelling, itchiness**, and **erythema of the buccal mucosa** with vesicles and shallow ulcers, occurring after orthodontic wire placement, strongly suggest an allergic reaction to materials in the wires (e.g., nickel). - The improvement with **cold foods** (vasoconstriction and soothing effect) and the absence of skin blistering with pressure (differentiating from bullous diseases) further support this diagnosis. *Vitamin deficiency* - While a **vegan diet** can predispose to certain vitamin deficiencies (e.g., B12), the sudden onset of localized oral swelling and itchiness is not typical. - Oral manifestations of vitamin deficiencies usually develop chronically and involve conditions like **glossitis, angular cheilitis, or stomatitis**, rather than acute localized swelling and vesicles. *Dermatitis herpetiformis* - This condition is characterized by intensely pruritic, vesicular lesions, primarily on **extensor surfaces** (elbows, knees, buttocks), and is strongly associated with **celiac disease**. - Oral lesions are uncommon, and the lack of systemic GI symptoms or characteristic skin distribution makes this diagnosis less likely. *Reactivation of varicella zoster virus* - Reactivation (shingles) typically causes a **unilateral, dermatomal rash** with painful vesicles, usually occurring in older or immunocompromised individuals. - The patient's age and healthy status, along with the bilateral involvement of the mouth and lips, do not fit the typical presentation of zoster reactivation. *Herpes labialis* - Caused by **Herpes Simplex Virus (HSV)**, it presents as clusters of painful vesicles, typically on the **lips or perioral region**. - While vesicles are present, the diffuse erythema and edema of the buccal mucosa and the clear association with orthodontic hardware placement make allergic contact dermatitis a more likely etiology.

Question 43: A 36-year-old woman is brought to the emergency room by her husband for “weird behavior" for the past several weeks. He reports that her right arm has been moving uncontrollably in a writhing movement and that she has been especially irritable. She has a history of depression, which was diagnosed 4 years ago and is currently being treated with sertraline. She denies any recent fever, trauma, infections, travel, weakness, or sensory changes. She was adopted so is unsure of her family history. Which of the following is the most likely explanation for her symptoms?

A. Frontotemporal lobe degeneration
B. Presence of misfolded proteins in the brain
C. Development of intracellular eosinophilic inclusions
D. CAG triplet expansion on chromosome 4 (Correct Answer)
E. GAA triplet expansion on chromosome 9

Explanation: ***CAG triplet expansion on chromosome 4*** - The patient's symptoms of **chorea** (uncontrolled writhing movements) and **irritability** (psychiatric changes) are classic manifestations of **Huntington's disease**. - **Huntington's disease** is an autosomal dominant neurodegenerative disorder caused by a **CAG trinucleotide repeat expansion** on **chromosome 4** in the *HTT* gene. *Frontotemporal lobe degeneration* - **Frontotemporal dementia** typically presents with prominent behavioral changes (disinhibition, apathy) or language difficulties (aphasia), but **chorea** is not a characteristic feature. - While psychiatric symptoms can occur, the specific motor dysfunction described points away from isolated frontotemporal degeneration. *Presence of misfolded proteins in the brain* - While **Huntington's disease** does involve misfolded huntingtin protein, this answer choice is too general and could apply to many neurodegenerative diseases like Alzheimer's (beta-amyloid, tau) or Parkinson's (alpha-synuclein). - It does not specify the unique genetic basis directly responsible for the observed symptoms in this case. *Development of intracellular eosinophilic inclusions* - **Intracellular eosinophilic inclusions**, specifically **Lewy bodies**, are characteristic of **Parkinson's disease** and **Lewy body dementia**. - These conditions primarily present with parkinsonism or dementia, not the prominent choreiform movements seen in this patient. *GAA triplet expansion on chromosome 9* - A **GAA triplet expansion on chromosome 9** is the genetic cause of **Friedreich's ataxia**, an autosomal recessive disorder. - Friedreich's ataxia typically presents with progressive **ataxia**, dysarthria, and loss of proprioception, not chorea or prominent psychiatric changes like irritability.

Question 44: Three days after undergoing laparoscopic colectomy, a 67-year-old man reports swelling and pain in his right leg. He was diagnosed with colon cancer 1 month ago. His temperature is 38.5°C (101.3°F). Physical examination shows swelling of the right leg from the ankle to the thigh. There is no erythema or rash. Which of the following is likely to be most helpful in establishing the diagnosis?

A. D-dimer level
B. Compression ultrasonography (Correct Answer)
C. CT pulmonary angiography
D. Transthoracic echocardiography
E. Blood cultures

Explanation: ***Compression ultrasonography*** - This patient's presentation with **unilateral leg swelling and pain** after surgery, especially given his recent **colon cancer diagnosis** (a hypercoagulable state), is highly suspicious for a **deep vein thrombosis (DVT)**. - **Compression ultrasonography** is the gold standard, non-invasive imaging modality for diagnosing DVT, allowing direct visualization of thrombi and assessing venous compressibility. *D-dimer level* - While a **positive D-dimer** indicates recent or ongoing clot formation, it is **non-specific** and can be elevated in many conditions, including surgery, cancer, and infection. - A normal D-dimer can rule out DVT in low-probability patients, but a high D-dimer in a high-probability patient (like this case) requires further imaging for confirmation, making it less definitive than ultrasound. *CT pulmonary angiography* - This imaging is used to diagnose a **pulmonary embolism (PE)**, which is a complication of DVT, but the primary symptoms here are localized to the leg. - While PE is a concern, diagnosing the source (DVT) in the leg is the immediate priority for treatment and prevention of future complications. *Transthoracic echocardiography* - **Echocardiography** evaluates cardiac structure and function and can sometimes detect large clots in the right heart leading to PE, but it is not the primary diagnostic tool for DVT in the leg. - It would be done if signs of cardiac strain or shunting associated with acute PE were prominent, which is not the case here. *Blood cultures* - **Blood cultures** are used to diagnose **bacteremia or sepsis**, which might explain a fever, but the prominent, unilateral leg swelling and pain are not typical for a primary infectious cause in the leg without local signs of cellulitis or abscess. - While a low-grade fever is present, the absence of erythema or rash makes a primary infectious etiology less likely than DVT given the risk factors.

Question 45: A 52-year-old woman with type 2 diabetes mellitus comes to the physician because of a 2-day history of blisters on her forearms and pain during sexual intercourse. Her only medications are metformin and glyburide. Examination reveals multiple, flaccid blisters on the volar surface of the forearms and ulcers on the buccal, gingival, and vulvar mucosa. The epidermis on the forearm separates when the skin is lightly stroked. Which of the following is the most likely diagnosis?

A. Behcet disease
B. Pemphigus vulgaris (Correct Answer)
C. Toxic epidermal necrolysis
D. Dermatitis herpetiformis
E. Lichen planus

Explanation: ***Pemphigus vulgaris*** - The presence of **flaccid blisters** on the skin, **oral and vulvar mucosal ulcers**, and a **positive Nikolsky sign** (epidermal separation with light stroking) are classic features of **pemphigus vulgaris**. - This autoimmune blistering disease is characterized by antibodies against **desmoglein 1 and 3**, leading to acantholysis within the epidermis. *Behcet disease* - Behcet disease is characterized by recurrent **oral ulcers**, genital ulcers, and uveitis, but it typically presents with deeper, painful ulcers rather than **flaccid blisters** and does not involve a positive Nikolsky sign. - Skin lesions in Behcet's disease often include **erythema nodosum** or papulopustular lesions, not thin-walled blisters. *Toxic epidermal necrolysis* - **Toxic epidermal necrolysis (TEN)** is a severe, life-threatening drug-induced reaction characterized by widespread **epidermal detachment** (often >30% body surface area) and mucosal involvement, but it typically presents with widespread, confluent erythema followed by sheet-like epidermal peeling, not distinct flaccid blisters. - The onset is usually acute following drug exposure, and patients are often critically ill with systemic symptoms; while this patient has blisters, the description of "multiple, flaccid blisters" and pain during intercourse points away from the acute, widespread, drug-induced skin necrosis of TEN. *Dermatitis herpetiformis* - **Dermatitis herpetiformis** typically presents with intensely **pruritic, erythematous papules and vesicles** symmetrically distributed on extensor surfaces, and it is strongly associated with **celiac disease**. - It does not usually cause **flaccid blisters** or a positive Nikolsky sign, and oral lesions are uncommon. *Lichen planus* - **Lichen planus** is characterized by **pruritic, purple, polygonal, planar papules and plaques** with fine white lines (Wickham striae) and can affect skin, hair, nails, and mucous membranes. - While oral lesions (lacy white networks) and vulvar involvement can occur, it typically does not present with **flaccid blisters** or a positive Nikolsky sign.

Question 46: A 32-year-old man comes to the emergency department for acute pain in the left eye. He reports having awoken in the morning with a foreign body sensation. He had forgotten to remove his contact lenses before sleeping. Following lens removal, he experienced immediate pain, discomfort, and tearing of the left eye. He reports that the foreign body sensation persists and that rinsing with water has not improved the pain. He has been wearing contact lenses for 4 years and occasionally forgets to remove them at night. He has no history of serious medical illness. On examination, the patient appears distressed with pain and photophobia in the left eye. Administration of a topical anesthetic relieves the pain. Visual acuity is 20/20 in both eyes. Ocular motility and pupillary response are normal. The corneal reflex is normal and symmetric in both eyes. Which of the following is most likely to establish the diagnosis in this patient?

A. CT scan of the orbit
B. Cultures of ocular discharge
C. Gonioscopy
D. Ocular ultrasonography
E. Fluorescein examination (Correct Answer)

Explanation: ***Fluorescein examination*** - The patient's symptoms (acute pain, foreign body sensation, tearing, photophobia after prolonged contact lens wear) are highly suggestive of a **corneal abrasion** or **ulcer**. - A **fluorescein examination** is the definitive diagnostic tool for identifying corneal epithelial defects. Fluorescein dye will stain areas where epithelial cells are missing, appearing as bright green under a cobalt blue light. *CT scan of the orbit* - A CT scan of the orbit is used to evaluate for **orbital cellulitis**, **fractures**, or **intraorbital foreign bodies**, which are not indicated by the patient's presentation. - The patient's symptoms are localized to the surface of the eye, and the foreign body sensation is due to direct epithelial damage, not a deeper orbital issue. *Cultures of ocular discharge* - While cultures may be necessary if a **corneal ulcer** with infection is suspected, the initial diagnostic step for identifying the defect itself is fluorescein staining. - Cultures would be performed after visualizing an ulcer and if there are signs of infection, such as purulent discharge or infiltrates. *Gonioscopy* - **Gonioscopy** is a specialized examination used to visualize the **anterior chamber angle** of the eye to assess for glaucoma or other angle abnormalities. - It is not indicated for the diagnosis of corneal surface defects like abrasions or ulcers. *Ocular ultrasonography* - **Ocular ultrasonography** is primarily used to visualize structures within the eye that cannot be seen due to opacities (e.g., dense cataracts, vitreous hemorrhage) or to assess for retinal detachments or tumors. - It is not useful for diagnosing surface corneal issues as presented in this case.

Question 47: A 53-year-old male presents to your office for abdominal discomfort. The patient states he first noticed pain on his right flank several months ago, and it has been gradually getting worse. For the past week, he has also noticed blood in his urine. Prior to this episode, he has been healthy and does not take any medications. The patient denies fever, chills, and dysuria. He has a 40 pack-year smoking history. Vital signs are T 37 C, BP 140/90 mmHg, HR 84/min, RR 14/min, O2 98%. Physical exam is unremarkable. CBC reveals a hemoglobin of 17 and hematocrit of 51%, and urinalysis is positive for red blood cells, negative for leukocytes. Which of the following is the most likely diagnosis?

A. Pyelonephritis
B. Renal oncocytoma
C. Renal cell carcinoma (Correct Answer)
D. Abdominal aortic aneurysm
E. Polycystic kidney disease

Explanation: ***Renal cell carcinoma*** - The classic triad of **flank pain**, **hematuria**, and a palpable abdominal mass (which may not always be present or detected on physical exam) - **Erythrocytosis** (high hemoglobin and hematocrit) due to increased **erythropoietin** production by the tumor, and a significant **smoking history** are strong indicators. *Pyelonephritis* - This is an infection of the kidney, typically presenting with **fever**, **chills**, **dysuria**, and flank pain. - The patient denies fever and chills, and the urinalysis is negative for leukocytes, making pyelonephritis unlikely. *Renal oncocytoma* - While it is a **renal tumor** that can cause flank pain or hematuria, it is typically **benign** and does not usually cause paraneoplastic syndromes like erythrocytosis. - In the presence of erythrocytosis and a strong smoking history, a malignant cause like RCC is more probable. *Abdominal aortic aneurysm* - An AAA can cause abdominal or flank pain, but it would not typically cause **hematuria** or **erythrocytosis**. - Rupture or dissection of an AAA presents as severe, acute pain and hemodynamic instability, which is not described. *Polycystic kidney disease* - This genetic disorder is characterized by multiple cysts in the kidneys, leading to pain, hematuria, and **renal failure over time**. - While it can cause hematuria, it is less likely to present with new-onset erythrocytosis and in a patient with no previous medical history.

Question 48: A 54-year-old man is brought by his family to the emergency department because of severe pain and weakness in his right leg. His symptoms have been gradually worsening over the past 5 weeks, but he did not seek medical care until today. He has a history of lower back pain and has no surgical history. He denies tobacco or alcohol use. His temperature is 37°C (98.6°F), the blood pressure is 140/85 mm Hg, and the pulse is 92/min. On physical examination, pinprick sensation is absent in the perineum and the right lower limb. Muscle strength is 2/5 in the right lower extremity and 4/5 in the left lower extremity. Ankle and knee reflexes are absent on the right side but present on the left. In this patient, magnetic resonance imaging (MRI) of the lumbar spine will most likely show which of the following?

A. Decreased spinal canal diameter
B. Focal demyelination of the spinal cord
C. Compression of the cauda equina (Correct Answer)
D. Compression of the conus medullaris
E. Sacroiliitis and enthesitis

Explanation: ***Compression of the cauda equina*** - The patient's symptoms of **bilateral leg weakness (worse on the right)**, **perineal sensory loss**, and **absent reflexes (right side)** are hallmark signs of **cauda equina syndrome**. - **MRI** is the gold standard for diagnosing cauda equina compression, which involves nerve roots below the L2 level. *Decreased spinal canal diameter* - While a decreased spinal canal diameter is seen in **spinal stenosis**, it typically causes neurogenic claudication (leg pain with walking, relieved by leaning forward) and less often acute, severe neurological deficits like those described. - The rapid onset of severe weakness and perineal numbness points away from typical chronic spinal stenosis. *Focal demyelination of the spinal cord* - **Focal demyelination** (as seen in multiple sclerosis) or transverse myelitis usually causes **upper motor neuron signs** (spasticity, hyperreflexia) below the level of the lesion, which contradicts the noted areflexia in this patient. - Cauda equina syndrome is a **lower motor neuron lesion**. *Compression of the conus medullaris* - **Conus medullaris compression** affects the terminal part of the spinal cord (T12-L2) and typically presents with **symmetrical symptoms**, more prominent bowel/bladder dysfunction, and often some **upper motor neuron signs** or **mixed upper and lower motor neuron signs**. - The patient's asymmetrical weakness and severe unilateral reflex loss are more indicative of cauda equina involvement. *Sacroiliitis and enthesitis* - **Sacroiliitis** (inflammation of the sacroiliac joints) and **enthesitis** (inflammation of tendon/ligament insertion sites) are characteristic of **spondyloarthropathies** like ankylosing spondylitis. - While these can cause back pain, they do not directly explain the severe neurological deficits, perineal sensory loss, and absent reflexes observed.

Question 49: A 52-year-old man is brought to the emergency department with a 2-hour history of severe, sudden-onset generalized headache. He has since developed nausea and has had one episode of vomiting. The symptoms began while he was at home watching television. Six days ago, he experienced a severe headache that resolved without treatment. He has hypertension and hyperlipidemia. The patient has smoked two packs of cigarettes daily for 30 years. His current medications include lisinopril-hydrochlorothiazide and simvastatin. His temperature is 38.1°C (100.6°F), pulse is 82/min, respirations are 16/min, and blood pressure is 162/98 mm Hg. The pupils are equal, round, and reactive to light. Fundoscopic examination shows no swelling of the optic discs. Cranial nerves II–XII are intact. He has no focal motor or sensory deficits. Finger-to-nose and heel-to-shin testing are normal. A CT scan of the head shows no abnormalities. Which of the following is the most appropriate next step in management?

A. Obtain an MRI scan of the head
B. Repeat CT scan in 24 hours
C. Administer 100% oxygen and intranasal sumatriptan
D. Place ventriculoperitoneal shunt
E. Obtain a lumbar puncture (Correct Answer)

Explanation: ***Obtain a lumbar puncture*** - The sudden onset of a "thunderclap" headache, especially if severe and generalized, is highly suspicious for **subarachnoid hemorrhage (SAH)**, even with a normal CT scan. An earlier, resolving headache ( sentinel headache) further supports this. - A **lumbar puncture (LP)** is the gold standard for diagnosing SAH when a CT scan is negative, as it can detect **xanthochromia** (yellowish discoloration of CSF due to bilirubin degradation of red blood cells), indicating prior bleeding. *Obtain an MRI scan of the head* - While an MRI can detect SAH, especially in later stages, it is **less sensitive than LP** for acute SAH, particularly within the first few hours or if the bleed is small. - MRI is generally reserved for situations where a CT scan is normal and LP is equivocal or contraindicated, or to investigate other potential causes of headache like lesions or thrombosis. *Repeat CT scan in 24 hours* - Repeating the CT scan in 24 hours is **not the most appropriate immediate action** as it will delay definitive diagnosis of SAH, which is a medical emergency requiring prompt management. - While a repeat CT might show subtle changes, an LP is a more sensitive and direct method to confirm or rule out SAH in this clinical scenario. *Administer 100% oxygen and intranasal sumatriptan* - This treatment is appropriate for **cluster headaches** or **migraine**, which typically have a different presentation (e.g., specific aura, unilateral pain, autonomic symptoms for cluster headache). - Given the high suspicion for SAH, administering these medications would delay proper diagnosis and management, which could be life-threatening. *Place ventriculoperitoneal shunt* - A ventriculoperitoneal shunt is used to treat **hydrocephalus**, a condition characterized by excessive CSF accumulation in the brain. - There are no clinical signs or symptoms (e.g., papilledema, altered mental status with focal neurological deficits) in this patient to suggest hydrocephalus requiring immediate shunting.

Question 50: A 37-year-old woman presents to the Emergency Department after 8 hours of left sided flank pain that radiates to her groin and pelvic pain while urinating. Her medical history is relevant for multiple episodes of urinary tract infections, some requiring hospitalization, and intravenous antibiotics. In the hospital, her blood pressure is 125/83 mm Hg, pulse of 88/min, a respiratory rate of 28/min, and a body temperature of 36.5°C (97.7°F). On physical examination, she has left costovertebral tenderness and lower abdominal pain. Laboratory studies include a negative pregnancy test, mild azotemia, and a urinary dipstick that is positive for blood. Which of the following initial tests would be most useful in the diagnosis of this case?

A. Urine osmolality
B. Fractional excretion of sodium (FeNa+)
C. Renal ultrasonography (Correct Answer)
D. Contrast abdominal computed tomography
E. Blood urea nitrogen (BUN): serum creatinine (SCr) ratio

Explanation: ***Renal ultrasonography*** - This is the most appropriate initial imaging test to evaluate for **kidney stones** (given the flank pain radiating to groin and hematuria) and **hydronephrosis** (which can indicate obstruction) and assess for signs of **pyelonephritis** (given the history of recurrent UTIs and CVA tenderness). - It is **non-invasive**, readily available, and avoids radiation exposure, making it suitable as a first-line diagnostic tool in this setting. *Urine osmolality* - This test primarily assesses the kidney's ability to **concentrate urine**, which is more relevant for evaluating fluid balance, diabetes insipidus, or other renal tubular disorders. - It would not directly diagnose the cause of acute flank pain or urinary tract obstruction. *Fractional excretion of sodium (FeNa+)* - FeNa+ is used to differentiate between **prerenal azotemia** and **acute tubular necrosis**, indicating the kidney's response to hypoperfusion. - While the patient has mild azotemia, FeNa+ would not identify the underlying cause of the flank pain, hematuria, or potential obstruction. *Contrast abdominal computed tomography* - While highly sensitive for diagnosing kidney stones and other renal pathologies, **contrast CT** exposes the patient to **ionizing radiation** and risks associated with contrast agents (e.g., contrast-induced nephropathy), especially with pre-existing azotemia. - It is often reserved for cases where ultrasound is inconclusive or more detailed anatomical information is needed. *Blood urea nitrogen (BUN): serum creatinine (SCr) ratio* - This ratio is primarily used to differentiate between **prerenal** causes of acute kidney injury (high ratio, e.g., >20:1) and **intrinsic renal** causes (lower ratio, e.g., <15:1). - While it can provide insight into the etiology of azotemia, it does not directly identify the cause of the patient's acute flank pain or potential urinary tract obstruction.

Question 51: A 25-year-old woman presents with slightly yellow discoloration of her skin and eyes. She says she has had multiple episodes with similar symptoms before. She denies any recent history of nausea, fatigue, fever, or change in bowel/bladder habits. No significant past medical history. The patient is afebrile and vital signs are within normal limits. On physical examination, she is jaundiced, and her sclera is icteric. Laboratory findings are significant only for a mild unconjugated hyperbilirubinemia. The remainder of laboratory results is unremarkable. Which of the following is the most likely diagnosis in this patient?

A. Crigler-Najjar syndrome type II
B. Crigler-Najjar syndrome type I
C. Gilbert syndrome (Correct Answer)
D. Hemolytic anemia
E. Physiological jaundice

Explanation: ***Gilbert syndrome*** - This syndrome is characterized by **mild, intermittent unconjugated hyperbilirubinemia**, often triggered by stress, fasting, or illness, and typically **without other symptoms** or signs of liver disease. - The patient's presentation with recurrent jaundice, absence of other symptoms, and normal liver function tests except for unconjugated hyperbilirubinemia are classic for **Gilbert syndrome**. *Crigler-Najjar syndrome type II* - While also involving unconjugated hyperbilirubinemia, **Crigler-Najjar type II** typically presents with more severe and persistent jaundice with higher bilirubin levels than seen in Gilbert syndrome. - This condition is rare and often requires intervention with **phenobarbital** to induce UGT1A1 activity, which is not indicated by the mild presentation here. *Crigler-Najjar syndrome type I* - This is a very severe and rare condition characterized by a **complete absence or near-complete absence of UGT1A1 activity**, leading to extremely high levels of unconjugated bilirubin from birth. - Patients typically develop **kernicterus** and often die in infancy or early childhood without aggressive treatment, which is inconsistent with the patient's age and mild symptoms. *Hemolytic anemia* - **Hemolytic anemia** causes unconjugated hyperbilirubinemia due to the breakdown of red blood cells, but it would also present with other signs such as **anemia**, **reticulocytosis**, and potentially splenomegaly, which are not mentioned. - The patient's laboratory results are otherwise unremarkable, ruling out red blood cell destruction as the primary cause. *Physiological jaundice* - **Physiological jaundice** is a common and transient condition in **newborns** due to immature liver function and increased red blood cell turnover. - It resolves within the first few weeks of life and is not applicable to a 25-year-old woman with recurrent episodes.

Question 52: A 67-year-old man presents with pain in both legs. He says the pain is intermittent in nature and has been present for approximately 6 months. The pain increases with walking, especially downhill, and prolonged standing. It is relieved by lying down and leaning forward. Past medical history is significant for type 2 diabetes mellitus, hypercholesterolemia, and osteoarthritis. The patient reports a 56-pack-year history but denies any alcohol or recreational drug use. His vital signs include: blood pressure 142/88 mm Hg, pulse 88/min, respiratory rate 14/min, temperature 37°C (98.6°F). On physical examination, the patient is alert and oriented. Muscle strength is 5/5 in his upper and lower extremities bilaterally. Babinski and Romberg tests are negative. Pulses measure 2+ in upper and lower extremities bilaterally. Which of the following is the next best step in the management of this patient?

A. MRI of the spine (Correct Answer)
B. CT angiography of the lower extremities
C. Ankle-brachial index
D. Cilostazol
E. Epidural corticosteroid injection

Explanation: ***MRI of the spine*** - The patient's symptoms of **intermittent leg pain worsened by walking (especially downhill) and prolonged standing**, and **relieved by lying down and leaning forward**, are highly classic for **neurogenic claudication** due to **lumbar spinal stenosis**. - An **MRI of the spine** is the *gold standard* for diagnosing spinal stenosis, clearly visualizing nerve root compression and the degree of canal narrowing. *CT angiography of the lower extremities* - This imaging is used to assess **peripheral artery disease** (PAD) but the patient's symptoms are inconsistent with vascular claudication. - **Vascular claudication** typically improves with rest, not with specific postures like leaning forward. *Ankle-brachial index* - The **ankle-brachial index (ABI)** is a non-invasive test to screen for **peripheral artery disease (PAD)**. - While the patient has risk factors for PAD (diabetes, hypercholesterolemia, smoking), his symptoms are classic for neurogenic claudication, and his **2+ pulses** in the lower extremities make PAD less likely. *Cilostazol* - **Cilostazol** is a phosphodiesterase inhibitor used to treat symptoms of **intermittent claudication** caused by **peripheral artery disease (PAD)**. - Since the patient's symptoms are more consistent with neurogenic claudication rather than vascular claudication, cilostazol would not be the appropriate initial step. *Epidural corticosteroid injection* - An **epidural corticosteroid injection** is a treatment option for symptomatic spinal stenosis but is not the *initial diagnostic step*. - Diagnosis with an **MRI** is necessary before considering targeted therapeutic interventions like injections.

Question 53: A 55-year-old man presents to the emergency department with fatigue and a change in his memory. The patient and his wife state that over the past several weeks the patient has been more confused and irritable and has had trouble focusing. He has had generalized and non-specific pain in his muscles and joints and is constipated. His temperature is 99.3°F (37.4°C), blood pressure is 172/99 mmHg, pulse is 79/min, respirations are 14/min, and oxygen saturation is 99% on room air. Physical exam is unremarkable. Laboratory studies are ordered as seen below. Hemoglobin: 9.0 g/dL Hematocrit: 30% Leukocyte count: 6,500/mm^3 with normal differential Platelet count: 166,000/mm^3 MCV: 78 fL Serum: Na+: 141 mEq/L Cl-: 103 mEq/L K+: 4.6 mEq/L HCO3-: 25 mEq/L BUN: 20 mg/dL Glucose: 99 mg/dL Creatinine: 0.9 mg/dL Ca2+: 10.2 mg/dL Which of the following is the most likely diagnosis?

A. Iron deficiency
B. Heavy metal exposure (Correct Answer)
C. Systemic lupus erythematosus
D. Guillain-Barre syndrome
E. Vitamin B12 deficiency

Explanation: ***Heavy metal exposure*** - The patient presents with **microcytic anemia** (Hemoglobin 9.0 g/dL, MCV 78 fL), **neuropsychiatric symptoms** (confusion, memory changes, irritability), **constipation**, **hypertension**, and **muscle/joint pain** - a constellation highly suggestive of **lead poisoning**. - **Lead poisoning** classically causes **microcytic anemia** (due to inhibition of heme synthesis), **neurological symptoms** (encephalopathy, cognitive dysfunction), **GI symptoms** (constipation, abdominal pain/"lead colic"), and **hypertension**. - The combination of **microcytic anemia with multisystem involvement** (CNS, GI, cardiovascular, musculoskeletal) points to **heavy metal toxicity** rather than simple iron deficiency. - Confirmatory testing would include **blood lead levels** and **peripheral blood smear** (showing basophilic stippling). *Iron deficiency* - While **iron deficiency** causes **microcytic anemia**, it does NOT adequately explain the **neuropsychiatric symptoms** (confusion, irritability, memory changes), **hypertension**, or the **severe constipation**. - Iron deficiency typically presents with **fatigue and weakness** but not the prominent **CNS dysfunction** seen in this patient. - The **multisystem involvement** suggests a toxic or systemic process rather than simple nutritional deficiency. *Systemic lupus erythematosus* - While **SLE** can cause fatigue and joint pain, it typically presents with **malar rash, photosensitivity, serositis, and specific autoantibodies**. - **SLE-associated anemia** is typically **normocytic** (anemia of chronic disease) or **hemolytic**, not microcytic. - The lack of typical **autoimmune features** makes this diagnosis less likely. *Guillain-Barre syndrome* - **GBS** presents with **acute ascending paralysis** and **areflexia** following an infection. - The patient's symptoms are **central** (confusion, memory issues), while **GBS affects the peripheral nervous system**. - **GBS does not cause anemia** or the constellation of symptoms described. *Vitamin B12 deficiency* - **Vitamin B12 deficiency** causes **macrocytic anemia** (elevated MCV), not microcytic. - The blood work shows **low MCV (78 fL)**, which rules out B12 deficiency. - Neurological symptoms of B12 deficiency include **subacute combined degeneration** (posterior column dysfunction), **paresthesias**, and **gait disturbances**, distinct from the presentation here.

Question 54: A 37-year-old man comes to the physician because of increasing swelling and pain of his right knee for the past month. He has not had any trauma to the knee or previous problems with his joints. He has hypertension. His only medication is hydrochlorothiazide. He works as a carpet installer. He drinks two to three beers daily. He is 170 cm (5 ft 7 in) tall and weighs 97 kg (214 lb); BMI is 33.6 kg/m2. His temperature is 37°C (98.6°F), pulse is 88/min, and blood pressure is 122/82 mm Hg. Examination of the right knee shows swelling and erythema; there is fluctuant edema over the lower part of the patella. The range of flexion is limited because of the pain. The skin over the site of his pain is not warm. There is tenderness on palpation of the patella; there is no joint line tenderness. The remainder of the examination shows no abnormalities. Which of the following is the most likely diagnosis?

A. Prepatellar bursitis (Correct Answer)
B. Septic arthritis
C. Gout
D. Osteoarthritis
E. Osgood-Schlatter disease

Explanation: ***Prepatellar bursitis*** - This patient's occupation as a **carpet installer** places him at high risk for **prepatellar bursitis**, which is often caused by repetitive kneeling, leading to inflammation of the bursa. - The examination findings of **swelling, erythema, and fluctuant edema over the lower part of the patella** with **no joint line tenderness** are highly consistent with prepatellar bursitis. *Septic arthritis* - **Septic arthritis** typically presents with severe pain, swelling, and **marked warmth** of the affected joint, along with systemic symptoms like fever, which are absent here. - While swelling is present, the **lack of warmth** and **fever**, and absence of joint line tenderness, make septic arthritis less likely. *Gout* - **Gout** typically presents with sudden onset of severe pain, redness, and swelling, most commonly affecting the **first metatarsophalangeal joint**, though it can affect the knee. - While factors like obesity, alcohol intake, and hydrochlorothiazide use increase gout risk, the **fluctuant edema** and absence of significant joint warmth are less characteristic of acute gouty arthritis. *Osteoarthritis* - **Osteoarthritis** usually presents with **gradual onset of joint pain** that worsens with activity and is relieved by rest, often with crepitus and limited range of motion. - It typically involves the **joint space** and would present with joint line tenderness, which is explicitly absent in this case. *Osgood-Schlatter disease* - **Osgood-Schlatter disease** is an **apophysitis of the tibial tubercle** involving inflammation where the patellar tendon attaches to the tibia, primarily seen in adolescents during growth spurts. - This condition is rare in adults, particularly in a 37-year-old male, and would typically present with pain localized to the **tibial tubercle**, not the patella itself.

Question 55: A 65-year-old woman comes to the physician for the evaluation of sharp, stabbing pain in the lower back for 3 weeks. The pain radiates to the back of her right leg and is worse at night. She reports decreased sensation around her buttocks and inner thighs. During the last several days, she has had trouble urinating. Three years ago, she was diagnosed with breast cancer and was treated with lumpectomy and radiation. Her only medication is anastrozole. Her temperature is 37°C (98.6°F), pulse is 80/min, respirations are 12/min, and blood pressure is 130/70 mm Hg. Neurologic examination shows 4/5 strength in the left lower extremity and 2/5 strength in her right lower extremity. Knee and ankle reflexes are 1+ on the right. The resting anal sphincter tone is normal but the squeeze tone is reduced. Which of the following is the most likely diagnosis?

A. Anterior spinal cord syndrome
B. Cauda equina syndrome (Correct Answer)
C. Conus medullaris syndrome
D. Central cord syndrome
E. Brown-sequard syndrome

Explanation: ***Cauda equina syndrome*** - The patient's presentation with **severe low back pain**, **saddle anesthesia** (decreased sensation around buttocks and inner thighs), **bladder dysfunction** (trouble urinating), and **motor weakness** in the lower extremities is highly indicative of cauda equina syndrome. This can be caused by **spinal metastases** from her breast cancer. - The **reduced squeeze tone** of the anal sphincter, despite normal resting tone, further supports the diagnosis, indicating dysfunction of the sacral nerve roots which are compressed in cauda equina syndrome. *Anterior spinal cord syndrome* - This syndrome typically presents with **motor paralysis**, loss of **pain** and **temperature** sensation below the lesion, but preservation of **proprioception** and **vibration sense**. - It does not typically cause **saddle anesthesia** or **bladder dysfunction** to the extent seen in this patient. *Conus medullaris syndrome* - Conus medullaris syndrome involves the lower part of the spinal cord (T12-L2) and typically presents with **symmetric motor weakness**, **early onset bladder and bowel dysfunction**, and often **perianal numbness**. - While there is bladder dysfunction, the described **asymmetric weakness** and prominent **radicular pain** radiating down one leg are more characteristic of cauda equina syndrome, which affects nerve roots rather than the spinal cord itself. *Central cord syndrome* - This syndrome usually results from hyperextension injuries and leads to **greater motor impairment in the upper extremities** than in the lower extremities. - It is often associated with a **'shawl-like' distribution** of sensory loss and does not typically present with the same severe lower extremity weakness, saddle anesthesia, or bladder dysfunction as seen in this patient. *Brown-Sequard syndrome* - This syndrome is characterized by **hemisection of the spinal cord**, resulting in **ipsilateral motor paralysis** and loss of **proprioception and vibration sensation** below the level of the lesion. - It also causes **contralateral loss of pain and temperature sensation** starting a few segments below the lesion, which does not match the patient's symptoms of bilateral sensory and motor deficits with saddle anesthesia.

Question 56: A 35-year-old male presents to his primary care physician with pain along the bottom of his foot. The patient is a long-time runner but states that the pain has been getting worse recently. He states that when running and at rest he has a burning and aching pain along the bottom of his foot that sometimes turns to numbness. Taking time off from training does not improve his symptoms. The patient has a past medical history of surgical repair of his Achilles tendon, ACL, and medial meniscus. He is currently not taking any medications. The patient lives with his wife and they both practice a vegan lifestyle. On physical exam the patient states that he is currently not experiencing any pain in his foot but rather is experiencing numbness/tingling along the plantar surface of his foot. Strength is 5/5 and reflexes are 2+ in the lower extremities. Which of the following is the most likely diagnosis?

A. Vitamin B12 deficiency
B. Common fibular nerve compression
C. Tarsal tunnel syndrome (Correct Answer)
D. Plantar fasciitis
E. Herniated disc

Explanation: ***Tarsal tunnel syndrome*** - The patient presents with **burning/aching pain** and **numbness/tingling along the plantar surface of the foot**, symptoms highly indicative of **tarsal tunnel syndrome**, which involves compression of the **posterior tibial nerve**. - His history of being a **long-time runner** and pain that doesn't improve with rest points to an overuse injury or nerve entrapment, fitting with tarsal tunnel syndrome. *Vitamin B12 deficiency* - While a vegan lifestyle can predispose to **vitamin B12 deficiency**, which causes neuropathy, the symptoms of **burning pain** and **numbness localized to the plantar foot** are more specific to nerve entrapment. - Neuropathy due to B12 deficiency typically presents as a more generalized **stocking-glove distribution**, rather than being confined to the sole of the foot. *Common fibular nerve compression* - Compression of the **common fibular nerve** (also known as the common peroneal nerve) typically affects the **dorsum of the foot** and the lateral aspect of the lower leg, leading to **foot drop** or weakness in dorsiflexion, which is not described. - The patient's symptoms are specifically on the **plantar surface**, inconsistent with common fibular nerve compression. *Plantar fasciitis* - **Plantar fasciitis** is characterized by **heel pain** that is typically worse with the **first steps in the morning** or after periods of rest, which improves with activity. - While it causes foot pain in runners, the prominent **numbness and tingling** described by the patient are not typical symptoms of plantar fasciitis. *Herniated disc* - A **herniated disc** causing radiating pain (sciatica) would involve symptoms that typically originate in the **lower back** or buttock and radiate down the leg. - While it can cause numbness, the **localization to the plantar foot** without accompanying back pain or proximal leg symptoms makes a herniated disc less likely.

Question 57: A 29-year-old woman comes to the physician because of a 2-day history of intermittent dark urine and mild flank pain. She has also had a cough, sore throat, and runny nose for the past 5 days. She has not had dysuria. She takes no medications. She has no known allergies. Her temperature is 37°C (98.6°F). Examination of the back shows no costovertebral angle tenderness. Laboratory studies show: Hemoglobin 10.4 g/dL Leukocyte count 8,000/mm3 Platelet count 200,000/mm3 Serum Na+ 135 mEq/L K+ 4.9 mEq/L Cl- 101 mEq/L HCO3- 22 mEq/L Urea nitrogen 18 mg/dL Creatinine 1.1 mg/dL Urine Color yellow Blood 3+ Protein 1+ Leukocyte esterase negative An ultrasound of the kidney and bladder shows no abnormalities. Which of the following is the most likely cause of this patient's symptoms?

A. Ischemic tubular injury
B. Urothelial neoplasia
C. Renal papillary necrosis
D. Renal glomerular damage (Correct Answer)
E. Interstitial renal inflammation

Explanation: ***Renal glomerular damage*** - The patient's symptoms (dark urine, mild flank pain) occurring shortly after an **upper respiratory infection** (cough, sore throat, runny nose) are highly suggestive of **acute glomerulonephritis**. - The urinalysis showing **hematuria (blood 3+) and proteinuria (protein 1+)** in the absence of dysuria or bacterial infection (leukocyte esterase negative, no CVA tenderness) points to glomerular inflammation as the cause of kidney involvement. *Ischemic tubular injury* - This condition typically presents with signs of **acute kidney injury**, such as elevated creatinine and blood urea nitrogen (BUN), which are not significantly altered here. - Urinalysis usually shows **muddy brown casts** and signs of tubular damage, rather than prominent hematuria and proteinuria alone. *Urothelial neoplasia* - While it can cause painless hematuria, it is less likely to present with concurrent **flu-like symptoms** and the rapid onset described. - Urothelial neoplasms are more common in older individuals or those with specific risk factors (e.g., smoking), and an **ultrasound revealed no abnormalities**. *Renal papillary necrosis* - This is typically seen in patients with **analgesic nephropathy**, sickle cell disease, or diabetes, none of which are indicated here. - It often leads to **gross hematuria** and passage of tissue fragments, and can be associated with severe pain, but the clinical picture does not fit this diagnosis. *Interstitial renal inflammation* - Acute interstitial nephritis is often caused by **drug reactions** or infections and is characterized by a significant inflammatory infiltrate in the renal interstitium. - While it can cause flank pain and hematuria, it more commonly presents with **fever, rash, and eosinophiluria**, and less often with prominent proteinuria like glomerulonephritis.

Question 58: A 45-year-old woman presents to her primary care physician for knee pain. She states that she has been experiencing a discomfort and pain in her left knee that lasts for several hours but tends to improve with use. She takes ibuprofen occasionally which has been minimally helpful. She states that this pain is making it difficult for her to work as a cashier. Her temperature is 98.6°F (37.0°C), blood pressure is 117/58 mmHg, pulse is 90/min, respirations are 14/min, and oxygen saturation is 97% on room air. Physical exam reveals a stable gait that the patient claims causes her pain. The patient has a non-pulsatile, non-erythematous, palpable mass over the posterior aspect of her left knee that is roughly 3 to 4 cm in diameter and is hypoechoic on ultrasound. Which of the following is associated with this patient's condition?

A. Venous valve failure
B. Herniated nucleus pulposus
C. Inflammation of the pes anserinus bursa
D. Artery aneurysm
E. Baker's cyst (Correct Answer)

Explanation: ***Baker's cyst*** - The patient's presentation of a **palpable, non-pulsatile, non-erythematous mass** in the posterior knee that is **hypoechoic on ultrasound** is highly suggestive of a Baker's cyst. - A Baker's cyst (popliteal cyst) is often associated with **underlying knee joint pathology**, such as osteoarthritis or meniscal tears, which can cause knee pain that improves with use and is worse with activity like standing for a cashier. *Venous valve failure* - **Venous valve failure** leads to **chronic venous insufficiency**, presenting as varicose veins, edema, skin changes (hyperpigmentation, lipodermatosclerosis), and ulcers, typically in the lower leg and ankle. - While it can cause leg discomfort, it does not typically manifest as a discreet, non-pulsatile mass in the posterior knee or be hypoechoic on ultrasound. *Herniated nucleus pulposus* - A **herniated nucleus pulposus** (slipped disc) causes **radicular pain** (sciatica) that radiates down the leg, numbness, tingling, and weakness, often exacerbated by sitting, coughing, or sneezing. - It would not present with a palpable mass in the posterior knee and is a spinal condition, not a direct knee pathology. *Inflammation of the pes anserine bursa* - **Pes anserine bursitis** causes pain and tenderness specifically on the **medial aspect of the knee**, about 2-3 inches below the joint line, where the pes anserinus tendons insert. - It would not cause a mass in the posterior knee and the pain location is distinct. *Artery aneurysm* - An **artery aneurysm**, particularly a popliteal artery aneurysm, would present as a **pulsatile mass** in the popliteal fossa. - Its pulsatile nature and the risk of rupture or thrombus formation distinguish it from the described non-pulsatile mass.

Question 59: A 43-year-old woman presents to the neurology clinic in significant pain. She reports a sharp, stabbing electric-like pain on the right side of her face. The pain started suddenly 2 weeks ago. The pain is so excruciating that she can no longer laugh, speak, or eat her meals as these activities cause episodes of pain. She had to miss work last week as a result. Her attacks last about 3 minutes and go away when she goes to sleep. She typically has 2–3 attacks per day now. The vital signs include: blood pressure 132/84 mm Hg, heart rate 79/min, and respiratory rate 14/min. A neurological examination shows no loss of crude touch, tactile touch, or pain sensations on the right side of the face. The pupillary light and accommodation reflexes are normal. There is no drooping of her mouth, ptosis, or anhidrosis noted. Which of the following is the most likely diagnosis?

A. Atypical facial pain
B. Cluster headache
C. Trigeminal neuralgia (Correct Answer)
D. Bell’s palsy
E. Basilar migraine

Explanation: ***Trigeminal neuralgia*** - The patient's presentation of sudden, sharp, stabbing, electric-shock-like pain on one side of the face, triggered by activities like speaking, eating, and laughing, is highly characteristic of **trigeminal neuralgia**. - The attacks are typically brief (lasting seconds to minutes), severe, and can cause significant functional impairment, consistent with the patient's report of missed work and inability to eat or speak. *Atypical facial pain* - This condition involves persistent, aching, or burning facial pain without clear neurological deficits, and it often does not have the paroxysmal, electric-shock quality seen in trigeminal neuralgia. - Unlike **trigeminal neuralgia**, atypical facial pain is usually continuous rather than episodic and is not typically triggered by specific activities. *Cluster headache* - Characterized by severe, unilateral pain, often periorbital or temporal, accompanied by autonomic symptoms such as **lacrimation, conjunctival injection, nasal congestion, rhinorrhea, sweating, miosis, ptosis, and eyelid edema**. - While very painful, the pain quality is usually deep and boring, not typically described as sharp, electric-shock like, and it is not triggered by facial movements like eating or speaking. *Bell’s palsy* - This condition involves **acute unilateral facial weakness or paralysis** due to inflammation of the facial nerve (CN VII), not pain as the primary symptom. - While some patients may experience mild pain around the ear, the hallmark is facial muscle weakness leading to drooping of the mouth and inability to close the eye, which are absent in this patient. *Basilar migraine* - A rare type of migraine with aura symptoms originating from the brainstem, including **vertigo, dysarthria, tinnitus, bilateral visual symptoms, ataxia, and sometimes decreased level of consciousness**. - While it can cause severe headache, it does not typically present with the described electric-shock-like facial pain triggered by movement, and the neurological examination did not reveal brainstem symptoms.

Question 60: A 60-year-old male is admitted to the ICU for severe hypertension complicated by a headache. The patient has a past medical history of insulin-controlled diabetes, hypertension, and hyperlipidemia. He smokes 2 packs of cigarettes per day. He states that he forgot to take his medications yesterday and started getting a headache about one hour ago. His vitals on admission are the following: blood pressure of 160/110 mmHg, pulse 95/min, temperature 98.6 deg F (37.2 deg C), and respirations 20/min. On exam, the patient has an audible abdominal bruit. After administration of antihypertensive medications, the patient has a blood pressure of 178/120 mmHg. The patient reports his headache has increased to a 10/10 pain level, that he has trouble seeing, and he can't move his extremities. After stabilizing the patient, what is the best next step to diagnose the patient's condition?

A. Doppler ultrasound of the carotids
B. CT head with intravenous contrast
C. MRI head without intravenous contrast
D. CT head without intravenous contrast (Correct Answer)
E. MRI head with intravenous contrast

Explanation: ***CT head without intravenous contrast*** - The sudden onset of severe headache, visual disturbances, and neurological deficits (inability to move extremities), coupled with uncontrolled severe hypertension despite initial treatment, is highly suggestive of an **intracranial pathology**, most likely a **hemorrhagic stroke**. - A **non-contrast CT scan of the head** is the **gold standard** for rapidly identifying acute intracranial hemorrhage, as it can be performed quickly and is readily available in emergency settings. *Doppler ultrasound of the carotids* - This test is primarily used to evaluate **carotid artery stenosis** due to atherosclerosis, which can lead to ischemic stroke. - While the patient has risk factors for atherosclerosis, his acute presentation with severe central neurological symptoms points more towards an acute intracranial event rather than carotid disease. *CT head with intravenous contrast* - While a contrast CT can be useful for identifying tumors, abscesses, or vascular malformations, it is **contraindicated in the initial assessment of acute stroke** if an intracranial hemorrhage is suspected. - Contrast can sometimes obscure subtle bleeds or complicate the interpretation of acute hemorrhage, and it also carries a risk of **contrast-induced nephropathy**, especially in a patient with diabetes. *MRI head without intravenous contrast* - An MRI provides superior soft tissue resolution compared to CT and is excellent for detecting ischemic strokes in later stages, as well as subtle hemorrhages, tumors, and other conditions. - However, it is **less available, takes longer to perform**, and is often not the first choice in an acute neurological emergency where time is critical, particularly when differentiating between ischemic and hemorrhagic stroke. *MRI head with intravenous contrast* - Similar to a contrast CT, an MRI with contrast is generally **not the initial imaging choice for acute stroke** due to time constraints and the need to quickly rule out hemorrhage before considering contrast administration. - Contrast agents for MRI, such as gadolinium, have their own risks, including **nephrogenic systemic fibrosis** in patients with renal impairment, which is a concern in a diabetic patient.

Question 61: A 33-year-old man presents to his primary care physician for left-sided knee pain. The patient has a history of osteoarthritis but states that he has been unable to control his pain with escalating doses of ibuprofen and naproxen. His past medical history includes diabetes mellitus and hypertension. His temperature is 102.0°F (38.9°C), blood pressure is 167/108 mmHg, pulse is 100/min, respirations are 14/min, and oxygen saturation is 98% on room air. Physical exam reveals a warm and tender joint that is very tender to the touch and with passive range of motion. The patient declines a gait examination secondary to pain. Which of the following is the best next step in management?

A. Colchicine
B. Antibiotics
C. Arthrocentesis (Correct Answer)
D. IV steroids
E. Rest, elevation, and ice

Explanation: ***Arthrocentesis*** - The patient presents with unilateral, **acutely painful**, **warm**, and **tender joint** along with **fever**, suggesting a possible **septic joint**. - **Arthrocentesis** is the definitive diagnostic procedure to rule out **septic arthritis** by analyzing synovial fluid for cell count, culture, and crystal analysis. *Colchicine* - Colchicine is used to treat **gout flares**; however, a definitive diagnosis of gout requires **synovial fluid analysis** for crystals, and **septic arthritis** must be ruled out first. - The patient's presentation with **fever** and **unilateral warmth/tenderness** makes **septic arthritis** a critical concern that takes precedence over presumptive gout treatment. *Antibiotics* - While **septic arthritis** is highly suspected, initiating antibiotics without **synovial fluid culture** is premature and can compromise diagnostic accuracy. - **Arthrocentesis** is necessary to identify the causative organism and guide appropriate **antibiotic therapy**. *IV steroids* - **Systemic steroids** could potentially worsen an underlying **septic infection** by suppressing the immune response. - They are used in inflammatory arthropathies, but **septic arthritis** must be excluded before considering such treatment. *Rest, elevation, and ice* - These are supportive measures for joint pain but do not address the underlying cause of the patient's acute, febrile joint pain, especially the potential for **septic arthritis**. - Delaying proper diagnosis and treatment of a **septic joint** can lead to significant morbidity including **joint destruction** and **sepsis**.

Question 62: A 23-year-old woman presents with a painful lesion in her mouth. She denies tooth pain, bleeding from the gums, nausea, vomiting, diarrhea, or previous episodes similar to this in the past. She states that her last normal menstrual period was 12 days ago, and she has not been sexually active since starting medical school 2 years ago. On physical examination, the patient has good dentition with no signs of infection with the exception of a solitary ulcerated lesion on the oral mucosa. The nonvesicular lesion has a clean gray-white base and is surrounded by erythema. Which of the following is correct concerning the most likely etiology of the oral lesion in this patient?

A. This lesion is non-contagious but will most likely recur. (Correct Answer)
B. This lesion is associated with an autoimmune disease characterized by a sensitivity to gluten.
C. This lesion may progress to squamous cell carcinoma.
D. This lesion is due to a fungal infection and may mean you're immunocompromised.
E. This lesion is highly contagious and is due to reactivation of a dormant virus.

Explanation: ***This lesion is non-contagious but will most likely recur.*** - The description of a **solitary, non-vesicular ulcerated lesion** with a **gray-white base** and surrounding **erythema** in the oral mucosa of a 23-year-old woman is highly characteristic of an **aphthous ulcer** (canker sore). - Aphthous ulcers are **non-contagious** and are well-known for their **recurrent nature**, often appearing periodically throughout a person's life. *This lesion is associated with an autoimmune disease characterized by a sensitivity to gluten.* - While **celiac disease** (an autoimmune condition triggered by gluten) can be associated with recurrent aphthous ulcers, it is not the **most likely direct etiology** of the lesion itself, especially without other gastrointestinal symptoms or a history of celiac disease. - The primary cause of aphthous ulcers in this context is typically unknown or related to minor trauma, stress, or nutritional deficiencies. *This lesion may progress to squamous cell carcinoma.* - Aphthous ulcers are **benign** and do not carry a risk of malignant transformation into **squamous cell carcinoma**. - Risk factors for squamous cell carcinoma of the oral cavity include prolonged tobacco and alcohol use, and chronic irritation from ill-fitting dentures. *This lesion is due to a fungal infection and may mean you're immunocompromised.* - A fungal infection like **oral candidiasis** (thrush) typically presents as **white patches** that can be scraped off, often associated with immunocompromise or antibiotic use. - The description of a well-demarcated ulcer with a gray-white base surrounded by erythema does not fit the typical presentation of a fungal infection. *This lesion is highly contagious and is due to reactivation of a dormant virus.* - Lesions caused by a dormant virus, such as **herpes simplex virus (HSV)**, typically present as **vesicles** that rupture to form ulcers, often appearing in clusters (cold sores). - Aphthous ulcers are distinctly **non-viral** in origin and **not contagious**, differentiating them from herpetic lesions.

Question 63: A 19-year-old girl comes to her physician with blurred vision upon awakening for 3 months. When she wakes up in the morning, both eyelids are irritated, sore, and covered with a dry crust. Her symptoms improve after she takes a hot shower. She is otherwise healthy and takes no medications. She does not wear contact lenses. Recently, she became sexually active with a new male partner. Her temperature is 37.4°C (99.3°F), and pulse is 88/minute. Both eyes show erythema and irritation at the superior lid margin, and there are flakes at the base of the lashes. There is no discharge. Visual acuity is 20/20 bilaterally. Which of the following is the next best step in management?

A. Lid hygiene and warm compresses (Correct Answer)
B. Topical erythromycin
C. Oral doxycycline
D. Topical mupirocin
E. Topical cyclosporine

Explanation: ***Lid hygiene and warm compresses*** - The patient's symptoms of **irritated, sore eyelids** with dry crusts upon awakening, improved by a hot shower, and flakes at the base of the lashes are classic for **blepharitis**. - **Lid hygiene** (e.g., gentle scrubbing with diluted baby shampoo) and **warm compresses** are the primary and most effective initial treatments for blepharitis to remove crusts and improve meibomian gland function. *Topical erythromycin* - Topical antibiotics like erythromycin are typically reserved for cases with signs of **bacterial infection** (e.g., purulent discharge, significant conjunctivitis), which are not present here. - While bacteria can contribute to blepharitis, hygiene is the first-line treatment unless infection is prominent. *Oral doxycycline* - **Oral doxycycline** is used for more severe or refractory cases of blepharitis, particularly those associated with **rosacea** or significant meibomian gland dysfunction that has not responded to conservative measures. - It works through its **anti-inflammatory** properties and reduction of bacterial lipase activity, but it's not the initial best step. *Topical mupirocin* - **Topical mupirocin** is an antibiotic primarily used for **skin infections** (e.g., impetigo) and is not a standard treatment for blepharitis unless there is a clear, localized staphylococcal skin infection that is not responding to other treatments. - It is not indicated for the general management of blepharitis. *Topical cyclosporine* - **Topical cyclosporine** is an **immunomodulator** used primarily for severe **dry eye disease** or ocular surface inflammation that has not responded to conventional treatments. - While blepharitis can contribute to dry eye, cyclosporine is not the initial treatment for blepharitis itself.

Question 64: A 43-year-old man comes to the physician for a follow-up examination. Four months ago, he was treated conservatively for ureteric colic. He has noticed during micturition that his urine is reddish-brown initially and then clears by the end of the stream. He has no dysuria. He has hypertension. His only medication is hydrochlorothiazide. He appears healthy and well-nourished. His temperature is 37°C (98.6°F), pulse is 80/min, and blood pressure is 122/86 mm Hg. Physical examination shows no abnormalities. Laboratory studies show: Hemoglobin 14.1 g/dL Serum Glucose 88 mg/dL Creatinine 0.6 mg/dL Urine Blood 2+ Protein negative Leukocyte esterase negative Nitrite negative RBCs 5–7/hpf WBCs 0–1/hpf RBC casts none Which of the following is the most likely origin of this patient's hematuria?

A. Urethra (Correct Answer)
B. Ureter
C. Urinary bladder
D. Renal pelvis
E. Renal glomeruli

Explanation: ***Urethra*** - **Initial hematuria** (blood at the beginning of urination that clears by the end) is the classic presentation of **urethral bleeding**. - Blood accumulated in the urethra is washed out at the start of micturition, with subsequent urine being clear once the urethral blood has been voided. - Common causes include urethral stricture, urethritis, or trauma. The history of ureteric colic is likely incidental and unrelated to the current hematuria pattern. *Urinary bladder* - Bladder pathology typically causes **terminal hematuria** (blood at the end of urination) when the bladder neck or trigone contracts at the end of voiding. - Bladder sources can also cause **total hematuria** (blood throughout the entire stream), but not the isolated initial hematuria pattern seen here. *Renal pelvis* - Hematuria from the renal pelvis presents as **total hematuria** because blood mixes with urine throughout the upper urinary tract. - The pattern of initial hematuria clearing by the end of the stream excludes an upper tract source. *Ureter* - Similar to renal pelvis bleeding, ureteral sources cause **total hematuria** as blood mixes with urine during flow from kidney to bladder. - The history of ureteric colic 4 months ago (now resolved) is not related to the current initial hematuria pattern. *Renal glomeruli* - Glomerular hematuria is characterized by **dysmorphic RBCs**, **RBC casts**, and often **proteinuria**—none of which are present. - Would present as **total hematuria** with cola-colored or tea-colored urine, not the initial-clearing pattern described.

Question 65: A 24-year-old woman presents to the emergency department for chest pain and shortness of breath. She was at home making breakfast when her symptoms began. She describes the pain as sharp and located in her chest. She thought she was having a heart attack and began to feel short of breath shortly after. The patient is a college student and recently joined the soccer team. She has no significant past medical history except for a progesterone intrauterine device which she uses for contraception, and a cyst in her breast detected on ultrasound. Last week she returned on a trans-Atlantic flight from Russia. Her temperature is 98.4°F (36.9°C), blood pressure is 137/69 mmHg, pulse is 98/min, respirations are 18/min, and oxygen saturation is 99% on room air. Physical exam reveals an anxious young woman. Cardiac and pulmonary exam are within normal limits. Deep inspiration and palpation of the chest wall elicits pain. Neurologic exam reveals a stable gait and cranial nerves II-XII are grossly intact. Which of the following best describes the most likely underlying etiology?

A. Ischemia of the myocardium
B. Clot in the pulmonary veins
C. Psychogenic etiology
D. Musculoskeletal inflammation
E. Clot in the pulmonary arteries (Correct Answer)

Explanation: ***Clot in the pulmonary arteries*** - This patient has **significant risk factors for pulmonary embolism (PE)**: recent **trans-Atlantic flight** (prolonged immobilization) and **progesterone IUD** (hormonal contraception increases thrombotic risk). - Classic PE symptoms include **acute-onset pleuritic chest pain** and **shortness of breath**, both present here. - **Key teaching point:** While the chest wall tenderness and normal vital signs might suggest a benign cause, **PE must be ruled out in high-risk patients** presenting to the ED with chest pain and dyspnea. Normal oxygen saturation and physical exam do not exclude PE. - The **Wells criteria** would assign points for recent travel and symptoms consistent with PE, warranting further workup (D-dimer, CT pulmonary angiography). - In emergency medicine, **risk factors take precedence** over reassuring physical findings when considering life-threatening diagnoses like PE. *Ischemia of the myocardium* - The patient is **24 years old** with no traditional cardiovascular risk factors (smoking, hypertension, diabetes, family history). - The pain is **sharp and pleuritic**, not the typical crushing, substernal pressure of acute coronary syndrome. - **Myocardial infarction is exceedingly rare** in this demographic without congenital abnormalities or cocaine use. *Clot in the pulmonary veins* - This represents an **anatomical misunderstanding** of PE pathophysiology. - **Venous thromboemboli form in systemic veins** (typically deep veins of legs) and travel through the right heart to lodge in the **pulmonary arteries**, not veins. - Pulmonary veins carry oxygenated blood from lungs to left atrium; obstruction here would cause pulmonary edema, not PE. *Psychogenic etiology* - While the patient appears **anxious**, attributing symptoms to panic/anxiety is a **diagnosis of exclusion**. - **Critical error:** Dismissing symptoms as psychogenic in a patient with **clear PE risk factors** could lead to catastrophic outcomes if PE is missed. - Panic attacks can mimic PE, but the recent flight and hormonal contraception mandate organic cause evaluation first. *Musculoskeletal inflammation* - The finding of **pain with palpation** and **deep inspiration** is classically associated with **costochondritis or chest wall strain**. - This is a **reasonable consideration** and in many patients would be the correct diagnosis. - **However:** The combination of **recent long-haul flight + hormonal contraception + acute dyspnea** creates a clinical scenario where PE **cannot be assumed away** based on chest wall tenderness alone. - Pleuritic chest pain can occur with PE when it causes pleural irritation, and **PE can coexist with incidental chest wall tenderness**. - The **standard of care** requires PE evaluation before attributing symptoms solely to musculoskeletal causes in this high-risk scenario.

Question 66: A 41-year-old woman with a past medical history significant for asthma and seasonal allergies presents with a new rash. She has no significant past surgical, social, or family history. The patient's blood pressure is 131/90 mm Hg, the pulse is 77/min, the respiratory rate is 17/min, and the temperature is 36.9°C (98.5°F). Physical examination reveals a sharply demarcated area of skin dryness and erythema encircling her left wrist. Review of systems is otherwise negative. Which of the following is the most likely diagnosis?

A. Scabies
B. Atopic dermatitis
C. Tinea corporis
D. Psoriasis
E. Contact dermatitis (Correct Answer)

Explanation: ***Contact dermatitis*** - The patient's presentation of a **sharply demarcated** area of **dryness and erythema** encircling her left wrist is highly suggestive of **contact dermatitis**, especially given her history of allergies. - This condition arises when skin comes into direct contact with an **irritating substance** or an **allergen**, and the **distribution** on the wrist strongly points to an external agent like jewelry or a watch strap. *Scabies* - **Scabies** typically presents with **intensely pruritic** papules and burrows, often in the **web spaces of fingers and toes**, wrists, and waistline. - The described rash in the patient lacks the characteristic **burrows** and the **generalized severe itching** associated with scabies. *Atopic dermatitis* - **Atopic dermatitis** (eczema) commonly manifests as **poorly demarcated**, erythematous, and pruritic patches, often with **excoriations** and **lichenification**, typically in **flexural areas** (e.g., antecubital and popliteal fossae). - While the patient has a history of asthma and allergies, the **sharply demarcated** nature and specific location of the rash on the wrist are less consistent with atopic dermatitis. *Tinea corporis* - **Tinea corporis** (**ringworm**) is a fungal infection characterized by an **annular shape** with an **elevated, scaly border** and central clearing. - The rash described in the patient lacks the **central clearing** and the typical **scaly, raised border** seen in tinea corporis. *Psoriasis* - **Psoriasis** typically presents as **well-demarcated**, erythematous plaques covered with **silvery scales**, often found on the **extensor surfaces** (e.g., elbows, knees) and scalp. - The rash in this patient does not mention the characteristic **silvery scales** or the common locations for psoriasis.

Question 67: A previously healthy 33-year-old woman comes to the physician because of pain and sometimes numbness in her right thigh for the past 2 months. She reports that her symptoms are worse when walking or standing and are better while sitting. Three months ago, she started going to a fitness class a couple times a week. She is 163 cm (5 ft 4 in) tall and weighs 88 kg (194 lb); BMI is 33.1 kg/m2. Her vital signs are within normal limits. Examination of the skin shows no abnormalities. Sensation to light touch is decreased over the lateral aspect of the right anterior thigh. Muscle strength is normal. Tapping the right inguinal ligament leads to increased numbness of the affected thigh. The straight leg test is negative. Which of the following is the most appropriate next step in management of this patient?

A. Advise patient to wear looser pants (Correct Answer)
B. Reduction of physical activity
C. MRI of the lumbar spine
D. X-ray of the hip
E. Blood work for inflammatory markers

Explanation: ***Advise patient to wear looser pants*** - This patient presents with symptoms consistent with **meralgia paresthetica**, a condition caused by compression of the **lateral femoral cutaneous nerve (LFCN)**. Modifying clothing or belts that compress the inguinal ligament can relieve pressure on the nerve. - Her increased weight, a recent increase in physical activity, and a positive Tinel's sign at the inguinal ligament (tapping leads to increased numbness) support this diagnosis. *Reduction of physical activity* - While excessive physical activity can contribute to meralgia paresthetica, simply reducing it without addressing the underlying compression might not fully resolve symptoms. - The patient has recently increased physical activity, which could be a contributing factor, but it's not the primary or most direct intervention for nerve compression. *MRI of the lumbar spine* - An MRI of the lumbar spine would be considered if there were signs of **radiculopathy** or other spinal pathology, such as weakness, reflex changes, or a positive straight leg test, which are absent here. - The symptoms are localized to the distribution of the LFCN, and the physical exam points away from a central spinal cause. *X-ray of the hip* - An X-ray of the hip would be indicated for suspected **hip joint pathology** or **bony abnormalities**, which are not suggested by the patient's symptoms (pain and numbness in the thigh, not hip joint pain). - Meralgia paresthetica is a nerve entrapment syndrome, not a structural issue of the hip joint. *Blood work for inflammatory markers* - Inflammatory markers like **ESR** or **CRP** would be relevant if an **inflammatory arthritis**, infection, or systemic inflammatory condition was suspected, but the patient's symptoms are purely neurological and localized. - There is no clinical evidence of inflammation, fever, or joint swelling to suggest an underlying inflammatory process.

Question 68: Nine days after being treated for a perforated gastric ulcer and sepsis, a 78-year-old woman develops decreased urinary output and malaise. She required emergency laparotomy and was subsequently treated in the intensive care unit for sepsis. Blood cultures grew Pseudomonas aeruginosa. The patient was treated with ceftazidime and gentamicin. She has type 2 diabetes mellitus, arterial hypertension, and osteoarthritis of the hips. Prior to admission, her medications were insulin, ramipril, and ibuprofen. Her temperature is 37.3°C (99.1°F), pulse is 80/min, and blood pressure is 115/75 mm Hg. Examination shows a healing surgical incision in the upper abdomen. Laboratory studies show: Hemoglobin count 14 g/dL Leukocyte count 16,400 mm3 Segmented neutrophils 60% Eosinophils 2% Lymphocytes 30% Monocytes 6% Platelet count 260,000 mm3 Serum Na+ 137 mEq/L Cl- 102 mEq/L K+ 5.1 mEq/L Urea nitrogen 25 mg/dL Creatinine 4.2 mg/dL Fractional excretion of sodium is 2.1%. Which of the following findings on urinalysis is most likely associated with this patient's condition?

A. RBC casts
B. WBC casts
C. Waxy casts
D. Muddy brown casts (Correct Answer)
E. Pigmented casts

Explanation: ***Muddy brown casts*** - The patient's presentation with **decreased urinary output**, **malaise**, and significantly **elevated creatinine** (4.2 mg/dL) after recent sepsis and treatment with nephrotoxic drugs (gentamicin) strongly suggests **acute tubular necrosis (ATN)**. - **Muddy brown casts** are pathognomonic for **acute tubular necrosis**, indicating damage to the renal tubules. *RBC casts* - **Red blood cell (RBC) casts** are indicative of **glomerulonephritis** or severe glomerular damage, which is not suggested by the clinical picture. - While the patient has hypertension and diabetes, her current acute kidney injury (AKI) is more consistent with ATN given the recent sepsis and aminoglycoside use. *WBC casts* - **White blood cell (WBC) casts** are characteristic of **pyelonephritis** (kidney infection) or **interstitial nephritis**. - Although she had sepsis, there is no direct evidence of pyelonephritis, and interstitial nephritis would present differently. *Waxy casts* - **Waxy casts** are associated with **chronic kidney disease** and indicate severe, longstanding tubular atrophy and urine stasis. - While she has risk factors for chronic kidney disease (diabetes, hypertension), her acute decline points to an acute process like ATN, making waxy casts less likely as the primary finding. *Pigmented casts* - **Pigmented casts** (e.g., myoglobin casts in rhabdomyolysis or hemoglobin casts in hemolysis) are seen in conditions involving the release of large amounts of pigments into the bloodstream. - While sepsis can cause hemolysis or muscle breakdown, **muddy brown casts** specifically refer to the granular, pigmented casts seen in ATN due to damaged tubular cells and heme pigments. "Pigmented casts" is a broader term, and "muddy brown casts" is more specific to ATN.

Question 69: A 19-year-old woman undergoes a laparoscopic appendectomy for acute appendicitis. During the procedure, a black, discolored liver is noted. Other than the recent appendicitis, the patient has no history of serious illness and takes no medications. She has no medication allergies. She does not drink alcohol or use illicit drugs. She has an uncomplicated postoperative course. At her follow-up visit 3 weeks later, her vital signs are within normal limits. Examination shows scleral icterus, which the patient states has been present for many years. Abdominal examination shows healing scars without drainage or erythema. Serum studies show: Aspartate aminotransferase 30 IU/L Alanine aminotransferase 35 IU/L Alkaline phosphatase 47 IU/L Total bilirubin 5.2 mg/dL Direct bilirubin 4.0 mg/dL Which of the following is the most likely diagnosis?

A. Gilbert syndrome
B. Rotor syndrome
C. Type II Crigler-Najjar syndrome
D. Dubin-Johnson syndrome (Correct Answer)
E. Wilson disease

Explanation: ***Dubin-Johnson syndrome*** - The key findings are **chronic intermittent jaundice** (scleral icterus for many years), **elevated direct bilirubin** (predominantly conjugated hyperbilirubinemia), normal liver enzymes, and a **black, discolored liver** noted during surgery. - This is an autosomal recessive disorder caused by a defect in the **MRP2 transporter**, leading to impaired biliary excretion of conjugated bilirubin and other organic anions. *Gilbert syndrome* - Characterized by **unconjugated hyperbilirubinemia** due to a defect in UDP-glucuronosyltransferase UGT1A1, which impairs bilirubin conjugation. - The patient here has predominantly **conjugated hyperbilirubinemia**, and the liver would appear grossly normal, not black. *Rotor syndrome* - Also presents with **conjugated hyperbilirubinemia**, but it does **not cause a black discoloration of the liver**. - It is caused by defects in hepatic organic anion transporting polypeptides (OATP1B1 and OATP1B3), leading to impaired hepatic storage and excretion of conjugated bilirubin. *Type II Crigler-Najjar syndrome* - This is characterized by **unconjugated hyperbilirubinemia** due to a partial deficiency of UDP-glucuronosyltransferase (UGT1A1), similar to Gilbert syndrome but more severe. - It does not cause a black liver, and the patient's bilirubin is primarily conjugated. *Wilson disease* - This is a disorder of **copper metabolism** that can cause liver disease (hepatitis, cirrhosis), neurological symptoms, and *Kayser-Fleischer rings*, but it does not cause a black liver or isolated conjugated hyperbilirubinemia. - Liver enzymes would typically be elevated in symptomatic Wilson disease.

Question 70: An 82-year-old male visits his primary care physician for a check-up. He reports that he is in his usual state of health. His only new complaint is that he feels as if the room is spinning, which has affected his ability to live independently. He is currently on lisinopril, metformin, aspirin, warfarin, metoprolol, and simvastatin and says that he has been taking them as prescribed. On presentation, his temperature is 98.8°F (37°C), blood pressure is 150/93 mmHg, pulse is 82/min, and respirations are 12/min. On exam he has a left facial droop and his speech is slightly garbled. Eye exam reveals nystagmus with certain characteristics. The type of nystagmus seen in this patient would most likely also be seen in which of the following diseases?

A. Benign paroxysmal positional vertigo
B. Multiple sclerosis (Correct Answer)
C. Meniere disease
D. Vestibular neuritis
E. Aminoglycoside toxicity

Explanation: ***Multiple sclerosis*** - This patient's presentation (acute vertigo, left facial droop, dysarthria, and nystagmus in an elderly patient with vascular risk factors) is most consistent with a **brainstem stroke** affecting the posterior circulation. - The nystagmus in this case is **central nystagmus**, characterized by being non-fatigable, multidirectional, and not suppressed by visual fixation—typical of **CNS lesions** affecting the brainstem or cerebellum. - **Multiple sclerosis** also causes **central nystagmus** due to demyelinating plaques in the brainstem, cerebellum, or medial longitudinal fasciculus, making it the condition that would exhibit the same type of nystagmus pattern. - Both brainstem stroke and MS produce central vestibular dysfunction with similar nystagmus characteristics. *Benign paroxysmal positional vertigo* - BPPV causes **peripheral nystagmus** that is fatigable, triggered by specific head positions, and typically resolves within 30-60 seconds. - The nystagmus is usually **rotatory or torsional** and follows a predictable pattern with the Dix-Hallpike maneuver. - This patient's persistent symptoms and additional neurological signs (facial droop, dysarthria) indicate a **central, not peripheral**, cause. *Meniere disease* - Meniere's disease causes **peripheral nystagmus** associated with episodic vertigo, fluctuating hearing loss, tinnitus, and aural fullness. - The nystagmus in Meniere's is typically **horizontal** during acute attacks but does not present with focal neurological deficits like facial weakness or speech changes. - This patient lacks the classic auditory symptoms and has clear signs of a **central lesion**. *Vestibular neuritis* - Vestibular neuritis results from inflammation of the vestibular nerve, causing **peripheral nystagmus** that is horizontal-torsional, unidirectional, and enhanced without visual fixation. - It typically presents with acute severe vertigo following a viral illness, without other neurological signs. - The presence of **facial droop and dysarthria** in this patient rules out a purely peripheral vestibular disorder. *Aminoglycoside toxicity* - Aminoglycosides cause **bilateral vestibulotoxicity**, leading to oscillopsia, chronic dysequilibrium, and possible hearing loss, but not acute vertigo with nystagmus. - When present, the vestibular dysfunction is typically **bilateral and symmetric**, without spontaneous nystagmus at rest. - This patient is not on aminoglycosides, and his presentation with focal neurological signs points to a **central structural lesion** rather than toxic peripheral vestibulopathy.

Question 71: A 79-year-old woman who lives alone is brought to the emergency department by her neighbor because of worsening confusion over the last 2 days. Due to her level of confusion, she is unable to answer questions appropriately. She has had type 2 diabetes mellitus for 29 years for which she takes metformin. Vital signs include: blood pressure 111/72 mm Hg, temperature 38.5°C (101.3°F), and pulse 100/min. Her fingerstick blood glucose is 210 mg/dL. On physical examination, she is not oriented to time or place and mistakes the nursing assistant for her cousin. Laboratory results are shown: Hemoglobin 13 g/dL Leukocyte count 16,000/mm3 Segmented neutrophils 70% Eosinophils 1% Basophils 0.3% Lymphocytes 25% Monocytes 4% Which of the following is the most likely diagnosis?

A. Brief psychotic disorder
B. Alzheimer's dementia
C. Delirium (Correct Answer)
D. Depression
E. Delusional disorder

Explanation: **Delirium** - The patient presents with **acute-onset confusion**, **disorientation** to time and place, and **misidentification of individuals**, all fluctuating symptoms characteristic of delirium. - The presence of **fever** (38.5°C), **leukocytosis** (16,000/mm³ with neutrophilia), and **hyperglycemia** (210 mg/dL) suggests an underlying acute medical condition (e.g., infection) as a precipitating factor for delirium in a vulnerable elderly patient with diabetes. *Brief psychotic disorder* - This disorder is characterized by the sudden onset of **psychotic symptoms** (e.g., delusions, hallucinations, disorganized speech) lasting less than 1 month, but it is not typically associated with an acute medical illness or systemic signs like fever and leukocytosis. - While the patient exhibits confusion, the clinical picture points more strongly to an acute organic cause rather than a primary psychiatric disorder. *Alzheimer's dementia* - Alzheimer's dementia typically manifests as a **gradual, progressive decline** in cognitive function over months to years, not an acute change in mental status over 2 days. - Although advanced dementia can present with confusion and disorientation, the acute onset, fluctuating nature, and signs of an underlying infection make delirium more likely. *Depression* - Depression in the elderly can sometimes cause **cognitive slowing** or **"pseudodementia,"** but it does not typically present with acute disorientation, fever, or leukocytosis. - The patient's presentation is more consistent with an acute confusional state rather than altered mood or anhedonia associated with depression. *Delusional disorder* - Delusional disorder involves **persistent, non-bizarre delusions** without other prominent psychotic symptoms or significant impairment in functioning, typically developing over a longer period. - The patient's global confusion, disorientation, and acute medical signs are inconsistent with a primary delusional disorder.

Question 72: A 27-year-old woman presents to her primary care physician for foot pain. The patient states that she has pain in her foot and toes whenever she exerts herself or is at work. The patient is an executive at a medical device company and works 60 hours/week. She is currently training for a marathon. She has a past medical history of anxiety, constipation, and irritable bowel syndrome. Her current medications include clonazepam, sodium docusate, and hyoscyamine. Her temperature is 99.5°F (37.5°C), blood pressure is 100/60 mmHg, pulse is 50/min, respirations are 10/min, and oxygen saturation is 99% on room air. Cardiac and pulmonary exams are within normal limits. Examination of the lower extremity reveals 5/5 strength with 2+ reflexes. Palpation of the interdigital space between the third and fourth toes elicits pain and a clicking sound. Which of the following is the most likely diagnosis?

A. Inflammation and damage to the plantar fascia
B. Intermetatarsal plantar nerve neuroma (Correct Answer)
C. Compression of the tibial nerve
D. Damage to the trabeculae of the calcaneus
E. Anterior talofibular ligament strain

Explanation: ***Intermetatarsal plantar nerve neuroma*** - The classic presentation of **Morton's neuroma** includes pain in the interdigital space, often between the third and fourth toes, exacerbated by activity, and relieved by rest. - The examination finding of pain and a **clicking sound** (Mulder's sign) upon palpation of the interdigital space specifically points towards an intermetatarsal plantar nerve neuroma. *Inflammation and damage to the plantar fascia* - **Plantar fasciitis** typically causes heel pain, especially with the first steps in the morning or after a period of rest. - While activity can worsen it, the pain is specifically localized to the **heel** or arch, not primarily between the toes, and a clicking sound is not characteristic. *Compression of the tibial nerve* - **Tarsal tunnel syndrome**, caused by compression of the tibial nerve, presents with pain, numbness, or tingling in the **arch and sole of the foot**. - It does not typically cause interdigital pain or a clicking sound during palpation between the toes. *Damage to the trabeculae of the calcaneus* - This describes a **stress fracture** of the calcaneus, which would cause diffuse deep heel pain, often with focal tenderness over the calcaneus. - It's less likely to present with interdigital pain or a specific clicking sign between the toes. *Anterior talofibular ligament strain* - A strain of the anterior talofibular ligament, common in **ankle sprains**, causes pain and swelling around the **lateral ankle**. - It does not cause pain between the toes or a palpable clicking sensation in that area.

Question 73: A 52-year-old man is brought to the emergency department with severe epigastric discomfort and left-sided chest pain radiating to the back that began after waking up. He has also vomited several times since the pain began. He underwent an esophagogastroduodenoscopy the previous day for evaluation of epigastric pain. He has ischemic heart disease and underwent a coronary angioplasty 3 years ago. His mother died of pancreatic cancer when she was 60 years old. His current medications include aspirin, clopidogrel, metoprolol, ramipril, and rosuvastatin. He is pale, anxious, and diaphoretic. His temperature is 37.9°C (100.2°F), pulse is 140/min, respirations are 20/min, and blood pressure is 100/60 mm Hg in his upper extremities and 108/68 mm Hg in his lower extremities. Pulse oximetry on room air shows oxygen saturation at 98%. An S4 is audible over the precordium, in addition to crepitus over the chest. Abdominal examination shows tenderness to palpation in the epigastric area. Serum studies show an initial Troponin I level of 0.031 ng/mL (N < 0.1 ng/mL) and 0.026 ng/mL 6 hours later. A 12-lead ECG shows sinus tachycardia with nonspecific ST-T changes. Which of the following is the most likely diagnosis?

A. Esophageal perforation (Correct Answer)
B. Pneumothorax
C. Aortic dissection
D. Acute pancreatitis
E. Acute myocardial infarction

Explanation: ***Esophageal perforation*** - The patient's recent **esophagogastroduodenoscopy (EGD)**, followed by severe epigastric and chest pain radiating to the back, vomiting, and **subcutaneous emphysema (crepitus)**, is highly suggestive of esophageal perforation. - **Mackler's triad** (vomiting, chest pain, and subcutaneous emphysema) is characteristic, and the overall clinical picture, including stable troponins and ECG, rules out cardiac events. *Pneumothorax* - While pneumothorax can cause chest pain and dyspnea, it typically presents with **diminished breath sounds** and **hyperresonance** on percussion, not crepitus over the chest (which indicates subcutaneous emphysema). - A recent EGD is not a direct risk factor for pneumothorax, and the pain radiation to the back is less typical for a simple pneumothorax. *Aortic dissection* - Aortic dissection presents with sudden, **excruciating tearing chest pain** radiating to the back, and can cause a pulse deficit or **blood pressure differential** between limbs. - While a slight BP differential is noted (100/60 vs 108/68), it's not significant enough for dissection, and the crepitus makes this diagnosis less likely without other definitive signs. *Acute pancreatitis* - Acute pancreatitis causes severe epigastric pain radiating to the back and vomiting, similar to this presentation. - However, the presence of **crepitus** (subcutaneous emphysema) and a recent EGD makes esophageal perforation a more likely diagnosis, as EGD is not a typical trigger for acute pancreatitis. *Acute myocardial infarction* - The patient has risk factors for cardiac disease, and initial symptoms like chest pain and diaphoresis could suggest an MI. - However, the **normal serial troponin levels** and **nonspecific ECG changes** rule out an acute myocardial infarction, especially given the presence of crepitus.

Question 74: A 58-year-old woman comes to the physician because of a 2-year history of progressively worsening pain in her knees and fingers. The knee pain is worse when she walks for longer than 30 minutes. When she wakes up in the morning, her fingers and knees are stiff for about 15 minutes. She cannot recall any trauma to the joints. She was treated with amoxicillin following a tick bite 2 years ago. She is otherwise healthy and only takes a multivitamin and occasionally acetaminophen for the pain. She drinks 1–2 glasses of wine daily. She is 160 cm (5 ft 3 in) tall and weighs 79 kg (174 lb); BMI is 31 kg/m2. Her temperature is 36.9°C (98.4°F), pulse is 70/min, and blood pressure is 133/78 mm Hg. Examination of the lower extremities reveals mild genu varum. Range of motion of both knees is limited; there is palpable crepitus. Complete flexion and extension elicit pain. Tender nodules are present on the proximal and distal interphalangeal joints of the index, ring, and little fingers bilaterally. Which of the following is the most likely diagnosis?

A. Septic arthritis
B. Lyme arthritis
C. Gout
D. Pseudogout
E. Osteoarthritis (Correct Answer)

Explanation: ***Osteoarthritis*** - The patient's presentation with **joint pain worse with activity**, **morning stiffness lasting less than 30 minutes**, **crepitus**, **limited range of motion**, **obesity**, and involvement of **DIP and PIP joints** (Heberden's and Bouchard's nodes) is classic for **osteoarthritis**. - **Genu varum** (bow-leggedness) is also a common feature of long-standing knee osteoarthritis. *Septic arthritis* - Septic arthritis typically presents acutely with **severe, acute pain**, swelling, warmth, and systemic symptoms like **fever and chills**, which are absent here. - It usually affects a **single joint** and is unlikely to present with chronic, bilateral, and polyarticular involvement over two years. *Lyme arthritis* - While the patient had a tick bite and received amoxicillin, **Lyme arthritis** often presents with **monoarticular** or **oligoarticular** large joint involvement, typically the knee, and usually has more significant effusions. - The chronic, progressive, and polyarticular nature involving DIPs and PIPs, along with short morning stiffness, is not typical for Lyme arthritis. *Gout* - Gout typically presents with **acute, excruciating pain** in a single joint (often the **first MTP joint**), intense inflammation, and rapid resolution of attacks. - The patient's chronic, symmetrical, and progressive pain, and morning stiffness are inconsistent with the typical presentation of gout. *Pseudogout* - Pseudogout (calcium pyrophosphate deposition disease) typically presents as **acute attacks** of pain and swelling, often in larger joints like the knee, wrist or shoulder, similar to gout. - While it can involve multiple joints, the chronic, progressive nature with specific involvement of DIPs and PIPs with osteoarthritic features (crepitus, activity-related pain, short morning stiffness) is more consistent with osteoarthritis.

Question 75: A 15-year-old Caucasian female presents with Parkinson-like symptoms. Serum analysis shows increased levels of free copper and elevated liver enzymes. What test would prove most helpful in diagnosing the patient's underlying disease?

A. Slit lamp examination (Correct Answer)
B. Reflex test
C. Serum detection of anti-myelin antibodies
D. Vitamin B12 test
E. CT scan

Explanation: ***Slit lamp examination*** - The constellation of **Parkinson-like symptoms**, **elevated free copper** and **liver enzymes** in a young patient strongly suggests **Wilson's disease**. - A slit lamp examination is crucial to detect **Kayser-Fleischer rings**, which are deposits of copper in the cornea and are pathognomonic for Wilson's disease. *Reflex test* - A reflex test assesses the integrity of the **peripheral nervous system** and **spinal cord reflexes**. - While neurological symptoms are present, a reflex test would not directly help diagnose the underlying metabolic disorder of copper accumulation. *Serum detection of anti-myelin antibodies* - Detecting anti-myelin antibodies is relevant for demyelinating diseases like **multiple sclerosis**. - This test is not indicated for a suspected **copper metabolism disorder** and would not explain the high free copper and liver enzyme levels. *Vitamin B12 test* - A Vitamin B12 test is used to diagnose **B12 deficiency**, which can cause neurological symptoms. - However, B12 deficiency does not lead to **elevated free copper** or **liver enzyme abnormalities**. *CT scan* - A CT scan of the brain could reveal **basal ganglia abnormalities** often seen in Wilson's disease. - However, a **slit lamp examination** for Kayser-Fleischer rings is a more specific and diagnostic test for Wilson's disease in this clinical context.

Question 76: A 67-year-old man presents to his primary care physician for fatigue. This has persisted for the past several months and has been steadily worsening. The patient has a past medical history of hypertension and diabetes; however, he is not currently taking any medications and does not frequently visit his physician. The patient has lost 20 pounds since his last visit. His laboratory values are shown below: Hemoglobin: 9 g/dL Hematocrit: 29% Mean corpuscular volume: 90 µm^3 Serum: Na+: 139 mEq/L Cl-: 100 mEq/L K+: 4.3 mEq/L Ca2+: 11.8 mg/dL Which of the following is the most likely diagnosis?

A. Intravascular hemolysis
B. Vitamin B12 and folate deficiency
C. Bone marrow aplasia
D. Malignancy (Correct Answer)
E. Iron deficiency

Explanation: **Malignancy** - The patient's **unexplained weight loss**, worsening fatigue, and **anemia** are highly suspicious for an underlying malignancy. - The elevated **calcium level (11.8 mg/dL)** suggests a paraneoplastic syndrome or bone involvement, which is common in many cancers (e.g., multiple myeloma, solid tumors with bony metastases). *Intravascular hemolysis* - This would typically present with signs of red blood cell destruction, such as **jaundice**, dark urine, and elevated **lactate dehydrogenase (LDH)**, none of which are mentioned. - The **normocytic anemia (MCV 90 µm^3)** is less typical for acute hemolysis, which can sometimes cause macrocytosis due to reticulocytosis. *Vitamin B12 and folate deficiency* - These deficiencies primarily cause **macrocytic anemia**, characterized by an **elevated mean corpuscular volume (MCV)**, which is not present here (MCV is 90 µm^3). - While fatigue can be a symptom, the unexplained weight loss and hypercalcemia point away from these as the primary diagnosis. *Bone marrow aplasia* - **Aplastic anemia** typically presents with **pancytopenia** (low red blood cells, white blood cells, and platelets), which is not indicated here beyond the anemia. - This condition does not directly explain the significant weight loss or hypercalcemia. *Iron deficiency* - **Iron deficiency anemia** is typically a **microcytic, hypochromic anemia**, meaning the **MCV would be low**, which is not the case here (MCV is 90 µm^3). - While it can cause fatigue, it does not explain the unexplained weight loss or hypercalcemia reported in this patient.

Question 77: A 45-year-old African-American woman presents with dyspnea, cough, and non-radiating chest pain. Her chest pain is relieved by leaning forward and worsens upon leaning backwards. A scratchy rub is heard best with the patient leaning forward. Physical examination did not elucidate evidence of a positive Kussmaul's sign, pulsus paradoxus, or pericardial knock. The patient most likely is suffering from which of the following?

A. Acute myocardial infarction
B. Constrictive pericarditis
C. Libman-Sacks endocarditis
D. Acute pericarditis (Correct Answer)
E. Cardiac tamponade

Explanation: **Correct Answer: Acute pericarditis** - Chest pain that is **relieved by leaning forward** and **worsens with leaning backward** is a classic symptom of pericarditis. - The presence of a **scratchy pericardial friction rub** highly suggests inflammation of the pericardial sac. - The absence of hemodynamic compromise signs (no pulsus paradoxus, no Kussmaul's sign) indicates acute inflammation without progression to tamponade or constriction. *Incorrect: Acute myocardial infarction* - Chest pain in **acute myocardial infarction** is typically described as crushing, substernal, and often radiates to the left arm, jaw, or back, and is not positionally relieved. - While dyspnea can occur, a **pericardial friction rub** is not a characteristic finding; it might be seen in post-infarction pericarditis (Dressler's syndrome), but not typically acutely. *Incorrect: Constrictive pericarditis* - This condition involves a **thickened, fibrotic pericardium** limiting diastolic filling, often presenting with signs of right heart failure like Kussmaul's sign and a pericardial knock, which are explicitly stated as absent here. - Chest pain is less prominent, and the **presenting friction rub** is characteristic of acute inflammation rather than chronic constriction. *Incorrect: Libman-Sacks endocarditis* - This is a form of **non-bacterial thrombotic endocarditis** typically associated with systemic lupus erythematosus, involving vegetations on heart valves. - It would not cause the classic positional chest pain or a widespread pericardial friction rub described, and its symptoms primarily relate to **embolic events** or valvular dysfunction. *Incorrect: Cardiac tamponade* - Cardiac tamponade is a life-threatening condition caused by **accumulated pericardial fluid** compressing the heart, leading to **Beck's triad** (hypotension, muffled heart sounds, JVD), pulsus paradoxus, and can include Kussmaul's sign, all explicitly noted as absent. - While it originates from pericardial effusion, the described **pericardial rub indicates inflammation** before significant effusion leading to tamponade has occurred.

Question 78: A 34-year-old G2P1 female at 37 weeks of gestation presents to the clinic for complaints of right-hand numbness and pain for the past month. She reports that the pain is usually worse at night and that she would sometimes wake up in the middle of the night from the “pins and needles.” She denies fever, weakness, or weight changes but endorses paresthesia and pain. The patient also reports a fall on her right hand 2 weeks ago. A physical examination demonstrates mild sensory deficits at the first 3 digits of the right hand but no tenderness with palpation. Strength is intact throughout. Which of the following findings would further support the diagnosis of this patient’s condition?

A. Tingling when the right wrist is percussed (Correct Answer)
B. Loss of sensation at the thenar eminence
C. Small cross-sectional area of the median nerve on ultrasonography
D. Hairline fracture of the scaphoid bone on magnetic resonance imaging (MRI)
E. Tingling when the wrists are flexed 90 degrees for 60 seconds

Explanation: ***Tingling when the right wrist is percussed*** - This describes a **positive Tinel's sign**, which is elicited by percussion over the **median nerve** at the wrist and is highly suggestive of **carpal tunnel syndrome**. - The patient's symptoms of **nocturnal pain**, **numbness**, and **paresthesia** in the first three digits are classic presentations of **median nerve compression** within the carpal tunnel. *Loss of sensation at the thenar eminence* - The **thenar eminence** receives innervation from the **palmar cutaneous branch of the median nerve**, which typically branches off *before* the carpal tunnel. - Thus, **sensation in the thenar eminence** is usually *preserved* in carpal tunnel syndrome, distinguishing it from more proximal median nerve lesions. *Small cross-sectional area of the median nerve on ultrasonography* - In **carpal tunnel syndrome**, the median nerve is **compressed and edematous**, leading to an *increase* in its **cross-sectional area** on ultrasonography, not a decrease. - A smaller cross-sectional area would indicate nerve atrophy or hypoplasia, which is inconsistent with acute compression. *Hairline fracture of the scaphoid bone on magnetic resonance imaging (MRI)* - While the patient reports a fall on her right hand, her symptoms are primarily **neuropathic** (numbness, pain, paresthesias in specific nerve distribution) rather than symptomatic of a **scaphoid fracture**. - A scaphoid fracture typically causes ** localized pain in the anatomical snuffbox**, tenderness, and difficulty with gripping, which are not highlighted in this patient's presentation. *Tingling when the wrists are flexed 90 degrees for 60 seconds* - This describes a **positive Phalen's sign**, which is a recognized diagnostic test for **carpal tunnel syndrome**, but the question asks for *additional findings* that would further support the diagnosis. - While positive, it describes a similar maneuver to Tinel's sign and doesn't offer as distinct a "further" supportive finding as Tinel's, especially given that Phalen's test assesses active symptom provocation (which is already described by the patient's complaints).

Question 79: A 35-year-old woman comes to the physician because of progressive left flank pain and increased urinary frequency for the past two weeks. Her appetite is normal and she has not had any nausea or vomiting. She has a history of type 1 diabetes mellitus that is poorly controlled with insulin. She is sexually active with her boyfriend, and they use condoms inconsistently. Her temperature is 38° C (100.4° F), pulse is 90/min, and blood pressure is 120/80 mm Hg. The abdomen is soft and there is tenderness to palpation in the left lower quadrant; there is no guarding or rebound. There is tenderness to percussion along the left flank. She complains of pain when her left hip is passively extended. Her leukocyte count is 16,000/mm3 and urine pregnancy test is negative. Urinalysis shows 3+ glucose. An ultrasound of the abdomen shows no abnormalities. Which of the following is the most likely diagnosis?

A. Psoas muscle abscess (Correct Answer)
B. Urinary tract infection
C. Ectopic pregnancy
D. Nephrolithiasis
E. Uterine leiomyoma

Explanation: ***Psoas muscle abscess*** - The patient presents with **left flank pain**, **fever**, **leukocytosis**, and pain with passive extension of the hip (the **psoas sign**), which are classic symptoms of a psoas abscess. - Her history of **poorly controlled type 1 diabetes mellitus** is a significant risk factor for compromised immunity and subsequent infections, including psoas abscesses. *Urinary tract infection* - While she has increased urinary frequency and flank tenderness, the presence of a strong **psoas sign** and normal abdominal ultrasound makes a complicated UTI like pyelonephritis less likely as the primary diagnosis, as pyelonephritis typically involves kidney issues visible on ultrasound. - Although the urinalysis is not provided, the combination of a negative abdominal ultrasound and a clear psoas sign points away from a simple or complicated UTI as the sole explanation. *Ectopic pregnancy* - An **ectopic pregnancy** is ruled out by the **negative urine pregnancy test**. - Symptoms of ectopic pregnancy typically include vaginal bleeding and severe abdominal pain, which are not described here. *Nephrolithiasis* - **Nephrolithiasis** (kidney stones) usually causes severe, colicky flank pain that often radiates to the groin, and may be associated with hematuria. - The abdominal ultrasound showing **no abnormalities** makes nephrolithiasis unlikely, as stones are typically visible on ultrasound. *Uterine leiomyoma* - **Uterine leiomyomas** (fibroids) are benign uterine tumors that can cause pelvic pain, heavy menstrual bleeding, or pressure symptoms, but they are not typically associated with fever, leukocytosis, or a positive psoas sign. - An abdominal ultrasound would likely show the fibroids if they were the cause of her symptoms.

Question 80: A 75-year-old man presents to the physician because of bloody urine, which has occurred several times over the past month. He has no dysuria, flank pain, nausea, or vomiting. He has no history of serious illness and takes no medications. He is a 40-pack-year smoker. The vital signs are within normal limits. Physical exam shows no abnormalities except generalized lung wheezing. The laboratory test results are as follows: Urine Blood 3+ RBC > 100/hpf WBC 1–2/hpf RBC casts Negative Bacteria Not seen Which of the following is the most appropriate diagnostic study at this time?

A. Intravenous (IV) pyelography
B. Computed tomography (CT) urogram
C. Cystoscopy (Correct Answer)
D. Chest X-ray
E. Ureteroscopy

Explanation: ***Cystoscopy*** - Given the patient's age, history of **40-pack-year smoking**, and **painless gross hematuria** without signs of infection or renal disease, there is a high suspicion for **bladder cancer**. - **Cystoscopy** is the **most appropriate initial diagnostic study** because it allows **direct visualization of the bladder mucosa** and enables **immediate biopsy** of any suspicious lesions. - The clinical presentation (painless hematuria + smoking history + absence of upper tract symptoms) strongly suggests a **bladder origin**, making cystoscopy the highest-yield diagnostic test. - Per **AUA guidelines**, cystoscopy is essential for all patients with gross hematuria and risk factors for urothelial malignancy. *Intravenous (IV) pyelography* - This older imaging modality has been **largely replaced by CT urogram** due to lower sensitivity and poorer visualization of both upper and lower urinary tract structures. - It cannot provide direct mucosal visualization or tissue diagnosis. *Computed tomography (CT) urogram* - A **CT urogram** is excellent for evaluating the **upper urinary tract** (kidneys, ureters) and is typically part of a complete hematuria workup. - However, when the clinical picture strongly suggests **bladder pathology** (as in this case), **cystoscopy is the more direct and definitive diagnostic test**. - CT urogram would be complementary imaging but cannot replace cystoscopy for evaluating the bladder mucosa and obtaining tissue diagnosis. - In practice, both studies are often performed, but cystoscopy is the **most appropriate initial study** for suspected bladder cancer. *Chest X-ray* - While the patient has **wheezing** (likely related to his smoking history), a chest X-ray does not evaluate the source of **hematuria**. - It might be useful for staging if bladder cancer is confirmed, but it is not the appropriate diagnostic study for evaluating urinary tract bleeding. *Ureteroscopy* - **Ureteroscopy** is indicated for evaluating and treating lesions within the **ureters or renal pelvis**, typically after imaging suggests an upper tract abnormality. - It is more invasive than cystoscopy and is not the first-line approach when clinical features point to a **bladder source**. - There are no signs suggesting upper tract pathology (no flank pain, no hydronephrosis).

Question 81: A 32-year-old woman comes to the emergency department because of a 12-hour history of a severe headache. She does not smoke or use illicit drugs. Her blood pressure at admission is 180/125 mm Hg. Physical examination shows a bruit in the epigastric region. Fundoscopy shows bilateral optic disc swelling. Which of the following investigations is most likely to confirm the diagnosis?

A. Serum 17-hydroxyprogesterone level
B. Oral sodium loading test
C. CT angiography (Correct Answer)
D. Echocardiography
E. Urinary catecholamine metabolites

Explanation: ***CT angiography*** - The patient presents with **severe hypertension** (180/125 mm Hg) with **papilledema** (optic disc swelling) indicating hypertensive emergency, along with a **critical finding of an epigastric bruit**. - An **epigastric or flank bruit** is highly specific for **renal artery stenosis**, which causes secondary hypertension due to renovascular disease. - In a **young woman (32 years old)**, the most likely cause is **fibromuscular dysplasia** of the renal arteries, which typically affects women of childbearing age. - **CT angiography** (or MR angiography) is the diagnostic test of choice to visualize the renal arteries and confirm **renal artery stenosis**, showing the characteristic "string of beads" appearance in fibromuscular dysplasia. *Urinary catecholamine metabolites* - This test is used to diagnose **pheochromocytoma**, which typically presents with **episodic (paroxysmal) hypertension** along with the classic triad of headache, palpitations, and diaphoresis. - **Pheochromocytoma does not cause an epigastric bruit**, which is the key differentiating feature in this case pointing toward a vascular etiology rather than a catecholamine-secreting tumor. *Serum 17-hydroxyprogesterone level* - This test is used to diagnose **congenital adrenal hyperplasia (CAH)**, a genetic disorder affecting adrenal steroid synthesis. - CAH does not present with acute hypertensive emergency and epigastric bruits as seen in this patient. *Oral sodium loading test* - This test is used to evaluate for **primary aldosteronism**, characterized by hypertension with hypokalemia and metabolic alkalosis. - Primary aldosteronism does not typically present with acute severe hypertensive crisis with papilledema, and **an epigastric bruit is not a feature** of this condition. *Echocardiography* - Echocardiography assesses **cardiac structure and function**, and may show left ventricular hypertrophy from chronic hypertension. - While it may reveal end-organ damage, it would not identify the underlying **renovascular cause** of the hypertension indicated by the epigastric bruit.

Question 82: A 57-year-old woman comes to the physician because of a 6-month history of tinnitus and progressive hearing loss in the left ear. She has type 2 diabetes mellitus and Raynaud syndrome. Her current medications include metformin, nifedipine, and a multivitamin. She appears well. Vital signs are within normal limits. Physical examination shows no abnormalities. A vibrating tuning fork is placed on the left mastoid process. Immediately after the patient does not hear a tone, the tuning fork is held over the left ear and she reports hearing the tuning fork again. The same test is repeated on the right side and shows the same pattern. The vibration tuning fork is then placed on the middle of the forehead and the patient hears the sound louder in the right ear. Which of the following is the most likely diagnosis?

A. Acoustic neuroma (Correct Answer)
B. Meningioma
C. Cerumen impaction
D. Ménière disease
E. Presbycusis

Explanation: ***Acoustic neuroma*** - The patient presents with **unilateral tinnitus** and **progressive sensorineural hearing loss** in the left ear, which is a classic presentation of an acoustic neuroma. - The **Rinne test** results (air conduction > bone conduction bilaterally) indicate **no conductive hearing loss**, while the **Weber test lateralizing to the right ear** confirms **sensorineural hearing loss in the left ear**. *Meningioma* - While a meningioma could present with neurological symptoms, it typically does not selectively cause **unilateral tinnitus** and **hearing loss** in this specific pattern without other focal neurological deficits. - Meningiomas are usually **slow-growing** and would likely present with mass effect symptoms, such as headache or seizures, depending on their location, which are not described here. *Cerumen impaction* - **Cerumen impaction** would cause a **conductive hearing loss**, where bone conduction would be *louder* than air conduction on the Rinne test (BC > AC). - The patient's Rinne test results (AC > BC) are consistent with **sensorineural hearing loss**, not conductive. *Ménière disease* - **Ménière disease** is characterized by episodic **vertigo, tinnitus, fluctuating hearing loss**, and aural fullness. - The patient's symptoms are primarily **progressive hearing loss** and constant tinnitus, without the episodic vertigo typical of Ménière disease. *Presbycusis* - **Presbycusis** is **age-related bilateral sensorineural hearing loss**, typically symmetric and affecting high frequencies. - The patient's symptoms are **unilateral** (affecting the left ear predominantly) and present with specific tuning fork findings that point to a localized lesion rather than general aging.

Question 83: A 31-year-old man comes to the physician because of pain, tingling, and numbness in his right hand that started 3 months ago. It is worse at night and frequently wakes him up. The symptoms can be relieved by shaking his hands but soon recur. He reports weakness of his right hand, especially when grasping objects. He has type 2 diabetes mellitus. His current medications are metformin and sitagliptin. Four months ago he went on a camping trip. He has been working as a hardscaper for 8 years. His temperature is 37.5°C (99.5°F), pulse is 86/min, and blood pressure is 110/70 mm Hg. Examination shows reproduction of his symptoms when his right hand is held above his head for 2 minutes. Laboratory studies show: Hemoglobin 13.2 g/dL Leukocyte count 7,600/mm3 Hemoglobin A1C 6.3% Erythrocyte sedimentation rate 13 mm/h Which of the following is most likely to confirm the diagnosis?

A. MRI of the head
B. Arterial Doppler ultrasonography
C. CT scan of cervical spine
D. Nerve conduction studies (Correct Answer)
E. ELISA for B. burgdorferi antibodies

Explanation: ***Nerve conduction studies*** - **Nerve conduction studies** are the most definitive diagnostic test for **carpal tunnel syndrome (CTS)**, confirming nerve entrapment and severity at the wrist. - The patient's symptoms of nocturnal pain and tingling, relief with shaking (**Flick sign**), weakness in grasping, and reproduction of symptoms with positional maneuvers (e.g., elevated arm test, akin to **Phalen's or Tinel's sign**) are highly characteristic of CTS. *MRI of the head* - An **MRI of the head** would be indicated for central neurological causes of numbness and weakness, such as stroke or brain tumor, which are not suggested by this patient's localized symptoms or a positive Flick sign. - Symptoms of **carpal tunnel syndrome (CTS)** are typically unilateral and peripheral, making central imaging an unlikely diagnostic tool for this presentation. *Arterial Doppler ultrasonography* - **Arterial Doppler ultrasonography** assesses blood flow in arteries and is used to diagnose peripheral arterial disease or vascular compromise. - The patient's symptoms are neurological (pain, tingling, numbness, weakness) and not vascular (e.g., claudication, pallor, diminished pulses). *CT scan of cervical spine* - A **CT scan of the cervical spine** would be used to evaluate **cervical radiculopathy**, which can mimic some symptoms of carpal tunnel. - However, the classic symptoms like nocturnal worsening, relief with shaking, and a positive elevated arm test are more specific to **CTS** than cervical radiculopathy. *ELISA for B. burgdorferi antibodies* - **ELISA for *B. burgdorferi*** antibodies is used to diagnose **Lyme disease**, which can cause neurological symptoms. - While the patient went on a camping trip, his symptoms are highly localized to the hand and consistent with a peripheral neuropathy, not the more diffuse or systemic symptoms of Lyme neuroborreliosis.

Question 84: A 62-year-old woman is brought to the emergency department because of sudden loss of vision in her right eye that occurred 50 minutes ago. She does not have eye pain. She had several episodes of loss of vision in the past, but her vision improved following treatment with glucocorticoids. She has coronary artery disease, hypertension, type 2 diabetes mellitus, and multiple sclerosis. She underwent a left carotid endarterectomy 3 years ago. She had a myocardial infarction 5 years ago. Current medications include aspirin, metoprolol, lisinopril, atorvastatin, metformin, glipizide, and weekly intramuscular beta-interferon injections. Her temperature is 36.8°C (98.2°F), pulse is 80/min, and blood pressure is 155/88 mm Hg. Examination shows 20/50 vision in the left eye and no perception of light in the right eye. The direct pupillary reflex is brisk in the left eye and absent in the right eye. The indirect pupillary reflex is brisk in the right eye but absent in the left eye. Intraocular pressure is 18 mm Hg in the right eye and 16 mm Hg in the left eye. A white, 1-mm ring is seen around the circumference of the cornea in both eyes. Fundoscopic examination of the right eye shows a pale, white retina with a bright red area within the macula. The optic disc appears normal. Fundoscopic examination of the left eye shows a few soft and hard exudates in the superior and nasal retinal quadrants. The optic disc and macula appear normal. Which of the following is the most likely diagnosis?

A. Central retinal artery occlusion (Correct Answer)
B. Acute angle-closure glaucoma
C. Central retinal vein occlusion
D. Vitreous hemorrhage
E. Central serous retinopathy

Explanation: ***Central retinal artery occlusion*** - The sudden, painless monocular vision loss, combined with the fundoscopic finding of a **pale, white retina** with a **"cherry-red spot"** (bright red area within the macula), is pathognomonic for central retinal artery occlusion (CRAO). - The patient's history of cardiovascular risk factors (coronary artery disease, hypertension, diabetes, carotid endarterectomy, myocardial infarction) increases the likelihood of **atheroembolic disease**, which is a common cause of CRAO. *Acute angle-closure glaucoma* - This condition typically presents with **sudden, severe eye pain**, blurred vision, halos around lights, and a **red eye**, often accompanied by nausea and vomiting, which are absent in this patient. - Ocular examination would usually reveal a **fixed, mid-dilated pupil** and significantly **elevated intraocular pressure**, whereas this patient's intraocular pressure is normal. *Central retinal vein occlusion* - While central retinal vein occlusion (CRVO) can cause sudden vision loss, the classic fundoscopic findings are **"blood and thunder" retina** (diffuse retinal hemorrhages, dilated tortuous veins, cotton wool spots, and optic disc edema). - The described **pale retina with a cherry-red spot** is not consistent with CRVO, but rather with arterial occlusion. *Vitreous hemorrhage* - Vitreous hemorrhage typically causes **sudden, painless vision loss**, often described as "floaters" or a "shower of black dots," and can obscure the red reflex. - Fundoscopic examination would show **blood within the vitreous cavity**, which might make it difficult to visualize the retina, and would not typically present with a pale retina and cherry-red spot. *Central serous retinopathy* - This condition is characterized by the **leakage of fluid under the retina**, leading to a serous detachment of the neurosensory retina or retinal pigment epithelium, causing blurred vision, metamorphopsia, and micropsia. - It usually affects younger to middle-aged males and does not cause the profound, sudden vision loss or the characteristic fundoscopic appearance of central retinal artery occlusion.

Question 85: A 13-year-old boy is brought to the physician because of a 1-month history of progressive difficulty breathing through his nose and a 2-week history of recurrent severe nosebleeds. When he holds the right nostril shut, he is unable to breathe nasally and his sense of smell is reduced. He has a 6-year history of asthma, which is well controlled with inhaled albuterol. Vital signs are within normal limits. Nasal inspection shows a pink, lobulated mass filling the left nasal cavity. The septum is deviated to the right side. The mass bleeds on touch. The remainder of the examination shows no abnormalities. Which of the following is the most appropriate next step in diagnosis?

A. Coagulation tests
B. Punch biopsy of the mass
C. CT scan of head with contrast (Correct Answer)
D. Genetic analysis of dynein genes
E. Sweat chloride test

Explanation: ***CT scan of head with contrast*** - A **CT scan with contrast** is the most appropriate next step to evaluate the extent of the nasal mass, assess for bone erosion, and differentiate between benign and malignant conditions, especially given the rapid progression and severe nosebleeds. - This presentation is classic for **juvenile nasopharyngeal angiofibroma (JNA)**, a benign but highly vascular tumor seen almost exclusively in adolescent males, characterized by unilateral nasal obstruction, epistaxis, and a lobulated mass. - Imaging will help characterize the mass, its origin, vascularity, and potential spread, which is crucial before any invasive procedures like a biopsy and may guide preoperative embolization if needed. *Coagulation tests* - While recurrent severe nosebleeds can sometimes suggest a **coagulopathy**, the presence of a large nasal mass with progressive obstruction points towards a structural cause rather than primarily a bleeding disorder. - Coagulation tests would be more appropriate if there were other signs of systemic bleeding or a known history of bleeding diathesis without a clear obstructing lesion. *Punch biopsy of the mass* - A **punch biopsy** carries a significant risk of severe bleeding given that the mass bleeds on touch, and its vascularity and extent are unknown. - For suspected JNA, biopsy is contraindicated due to the risk of catastrophic hemorrhage; imaging should always precede any tissue sampling to properly plan the procedure and minimize complications. *Genetic analysis of dynein genes* - **Dynein gene mutations** are associated with primary ciliary dyskinesia, which can cause chronic sinusitis and nasal polyps, but not typically a rapidly growing, bleeding, lobulated mass with unilateral obstruction in a 13-year-old. - The clinical picture strongly suggests a localized mass effect rather than a generalized ciliary dysfunction. *Sweat chloride test* - A **sweat chloride test** is used to diagnose cystic fibrosis, which can lead to chronic rhinosinusitis and nasal polyps, often bilateral. - The presentation of a unilateral, rapidly growing, bleeding mass is not typical for cystic fibrosis-related nasal polyps; therefore, it's not the most appropriate initial diagnostic step.

Question 86: A 50-year-old man comes to the emergency department for evaluation of right-sided facial weakness that he noticed after waking up. One month ago, he also experienced right-sided neck pain and headache that began after returning from a hunting trip to New Hampshire the week before. He took ibuprofen to relieve symptoms, which subsided a week later. He has a 5-year history of hypertension controlled with drug therapy. He has smoked one pack of cigarettes daily for 35 years and he drinks two beers daily. His vital signs are within the normal range. Physical examination shows right-sided drooping of the upper and lower half of the face. The patient has difficulties smiling and he is unable to close his right eye. The remainder of the examination shows no abnormalities. Which of the following is the most appropriate next step in diagnosis?

A. Noncontrast CT
B. Cerebrospinal fluid analysis
C. Western blot
D. Polymerase chain reaction of the facial skin
E. Enzyme-linked immunosorbent assay (Correct Answer)

Explanation: ***Enzyme-linked immunosorbent assay*** - The patient's presentation with **right-sided facial weakness affecting both upper and lower halves of the face**, along with a history of **neck pain and headache after a hunting trip to New Hampshire** (an endemic area for Lyme disease), strongly suggests **Lyme disease-associated Bell's palsy**. - An **ELISA** is the appropriate initial test for **Lyme disease screening**, detecting antibodies against *Borrelia burgdorferi*. *Noncontrast CT* - A **noncontrast CT scan of the brain** is primarily used to rule out acute intracranial pathologies like **hemorrhage** or **large strokes**. - In this case, the isolated facial paralysis without other focal neurological deficits or signs of acute stroke makes a CT less immediately relevant as the first diagnostic step. *Cerebrospinal fluid analysis* - **CSF analysis** would be considered if there were signs of **meningitis** or **encephalitis**, or if Lyme disease was strongly suspected but initial serological tests were negative. - It is not the most appropriate initial diagnostic step for isolated facial palsy. *Western blot* - A **Western blot** is used as a **confirmatory test** for Lyme disease, typically performed after a positive or indeterminate **ELISA result**. - It differentiates specific antibodies, but it is not the initial screening test. *Polymerase chain reaction of the facial skin* - **PCR of facial skin** is not a standard diagnostic test for facial palsy or Lyme disease, as the disease is systemic and not localized to a skin lesion in this context. - **Skin biopsy PCR** might be used to confirm an erythema migrans rash, which is not present here.

Question 87: A 50-year-old woman comes to the physician because of blisters on her forearm that appeared 3 days ago. She also reports pain in her left cheek when eating and pain during sexual intercourse for the past week. She has not been sick for the past 6 months. She has started hiking in the woods on the weekends with her son a couple months ago but has been careful to avoid poison ivy. She has a history of hypertension and osteoarthritis. She recently started taking captopril and stopped taking meloxicam 2 weeks ago. She has a family history of pernicious anemia and Graves' disease. The patient's vital signs are within normal limits. Examination reveals multiple, flaccid blisters on the volar surface of the forearm and ulcers on the buccal, gingival, and vulvar mucosa. The epidermis on the forearm separates when the skin is lightly stroked. The total body surface area involvement of the blisters is estimated to be 10%. The remainder of the examination shows no abnormalities. Which of the following is the most likely diagnosis?

A. Bullous pemphigoid
B. Toxic epidermal necrolysis
C. Dermatitis herpetiformis
D. Pemphigus vulgaris (Correct Answer)
E. Lichen planus

Explanation: ***Pemphigus vulgaris*** - The presence of **flaccid blisters** on the forearm, along with **oral and vulvar mucosal ulcers**, is highly characteristic of pemphigus vulgaris. Oral lesions often precede skin lesions, and the **Nikolsky sign** (epidermal separation with light stroking) is positive. - This autoimmune blistering disease is caused by antibodies against **desmoglein 1 and 3**, leading to acantholysis (loss of cohesion between keratinocytes) in the epidermis. The Captopril use is notable as ACE inhibitors can rarely trigger pemphigus. *Bullous pemphigoid* - Bullous pemphigoid typically presents with **tense bullae** that do not rupture easily and are often accompanied by **pruritus**, which is not described here, and a negative Nikolsky sign. - Mucosal involvement is less common and usually less severe than in pemphigus vulgaris, often sparing the oral cavity. *Toxic epidermal necrolysis* - This condition is characterized by widespread **erythema and epidermal detachment** (often >30% body surface area), usually triggered by medications, with prominent systemic symptoms (e.g., fever, malaise). The patient's 10% BSA involvement and lack of systemic illness makes this less likely. - The lesions in TEN are typically diffuse and rapidly progressing, resembling a severe burn, unlike the more localized flaccid blisters seen here. *Dermatitis herpetiformis* - Dermatitis herpetiformis presents as intensely **pruritic vesicles and papules**, primarily on extensor surfaces, and is strongly associated with **celiac disease**. - The blisters are typically firm and grouped, and mucosal lesions are uncommon, differentiating it from the flaccid blisters and mucosal ulcers described. *Lichen planus* - Lichen planus manifests as **pruritic, polygonal, planar, purple papules and plaques**, often with **Wickham's striae**. - While it can cause oral mucosal lesions (reticular white patches) and erosions, it does not typically present with the widespread flaccid blisters or positive Nikolsky sign seen in this patient.

Question 88: A 65-year-old woman comes to the clinic for an annual well-check. Her past medical history includes diabetes and hypertension, which are well-controlled with metformin and losartan, respectively. The patient reports a healthy diet consisting of mainly vegetables and lean meat. She denies smoking or alcohol use. She enjoys taking walks with her husband and sunbathing. Physical examination is unremarkable except for a rough, scaly, sandpaper-like plaque on her left dorsal hand with no tenderness or pain. What is the most likely diagnosis?

A. Rosacea
B. Sunburn
C. Seborrheic keratosis
D. Actinic keratosis (Correct Answer)
E. Psoriasis

Explanation: ***Actinic keratosis*** - The lesion description of a **rough**, **scaly**, **sandpaper-like plaque** on the **dorsal hand** is classic for an actinic keratosis. - The patient's history of **sunbathing** and age (65 years old) are significant risk factors, as actinic keratosis is caused by **chronic sun exposure** and is a precursor to squamous cell carcinoma. *Rosacea* - Rosacea typically presents with **facial erythema**, **telangiectasias**, papules, and pustules, primarily affecting the central face. - It does not present as a rough, scaly plaque on the dorsal hand. *Sunburn* - A sunburn is characterized by **erythema**, **pain**, and sometimes blistering, appearing acutely after sun exposure. - The lesion described is a chronic plaque, not an acute burn. *Seborrheic keratosis* - Seborrheic keratoses are typically described as "stuck-on" lesions with a **warty** or **greasy appearance**, often pigmented. - They do not usually have a "sandpaper-like" texture and are not directly caused by sun exposure, although they can occur in sun-exposed areas. *Psoriasis* - Psoriasis presents as **well-demarcated**, **erythematous plaques** with prominent **silvery scales**, often found on extensor surfaces, scalp, and nails. - The lesion described lacks the characteristic silvery scales and is not typically isolated to a single, small, rough plaque on the dorsal hand in this manner.

Question 89: A 28-year-old female presents to her primary care physician because of pain on her right foot. She says that the pain began 2 weeks ago and gets worse with weight bearing. She has been training for a marathon, and this pain has limited her training. On exam, there are no signs of inflammation or deformities on her foot. Compression of the forefoot with concomitant pressure on the interdigital space reproduces the pain on the plantar surface between the third and fourth toes and produces an audible click. What is the cause of this patient's condition?

A. Inflammation and scarring of the plantar fascia
B. A metatarsal compression fracture
C. Inflammation of the bursa
D. A bony outgrowth
E. A benign neuroma (Correct Answer)

Explanation: ***A benign neuroma*** - The patient's presentation with **forefoot pain**, worse with **weight-bearing**, and the presence of an **audible click** (Mulder's sign) upon compression of the interdigital space, specifically between the third and fourth toes, are classic signs of **Morton's neuroma**, which is a benign fibrotic enlargement of the common plantar nerve. - This condition is common in runners due to repetitive trauma and compression of the digital nerves. *Inflammation and scarring of the plantar fascia* - This description refers to **plantar fasciitis**, which typically causes pain in the **heel**, especially with the first steps in the morning or after rest. - While also common in runners, plantar fasciitis pain is usually not localized to the interdigital space and does not present with Mulder's click. *A metatarsal compression fracture* - A metatarsal stress fracture would present with **localized pain** and tenderness over the affected metatarsal bone, often worse with activity, but it typically doesn't involve an interdigital click or pain reproduction by compressing the forefoot in this specific manner. - Imaging like X-rays or MRI would confirm a stress fracture. *Inflammation of the bursa* - While bursitis can occur in the foot, **intermetatarsal bursitis** might cause pain in the interdigital space, but it usually doesn't involve the characteristic **Mulder's sign** or the specific nerve-related symptoms seen in a neuroma. - The primary issue with Morton's neuroma is nerve enlargement, not just bursal inflammation. *A bony outgrowth* - A bony outgrowth, such as a **bone spur** or **exostosis**, would typically cause pain due to mechanical irritation or compression of surrounding structures. - It would not typically present with a **Mulder's click** or the specific pain pattern associated with interdigital nerve compression characteristic of a neuroma.

Question 90: A 46-year-old male presents with his wife to his primary care provider for depression and strange movements. His wife reports that her husband has not been himself for the last two months. Whereas he was previously outgoing and “the life of the party,” the patient is now irritable and withdrawn. He is a partner at an accounting firm, but his colleagues are threatening his job if he continues to perform poorly at work. The patient cannot explain the recent changes to his mood and tearfully admits he fears there is something seriously wrong with him. His wife says that she thinks he is getting worse. The patient’s past medical history is significant for hypertension, for which he takes lisinopril. His family history is unknown as he was adopted. The patient met his mother once, and never knew his father but was told he died in his 50's. He drinks a few glasses of wine per week and has never smoked. On physical exam, the patient has a flat affect with facial grimace and sudden jerky movements of his upper extremities. Which of the following is most likely to be seen on further workup?

A. Alpha-synuclein aggregates on brain biopsy
B. Dorsal striatum atrophy on head CT (Correct Answer)
C. Positive 14-3-3 CSF assay
D. Neurofibrillary tangles on brain biopsy
E. Frontotemporal atrophy on head CT

Explanation: ***Dorsal striatum atrophy on head CT*** - The clinical presentation of **involuntary jerky movements (chorea)**, **psychiatric changes (depression, irritability, flat affect)**, and **cognitive decline (poor work performance)** in a relatively young patient with a family history suggestive of premature death points to **Huntington's disease**. - **Huntington's disease** is characterized by preferential **atrophy of the caudate and putamen** (components of the dorsal striatum), which can be visualized on CT or MRI of the head. *Alpha-synuclein aggregates on brain biopsy* - **Alpha-synuclein aggregates** are characteristic of **Lewy body diseases**, such as **Parkinson's disease** and **dementia with Lewy bodies (DLB)**. - While patients with these conditions can have cognitive and psychiatric symptoms, the prominent **chorea** described is not typical. *Positive 14-3-3 CSF assay* - A **positive 14-3-3 protein assay in CSF** is a marker for **Creutzfeldt-Jakob disease (CJD)**, a rapidly progressive prion disease. - CJD typically presents with **rapidly progressive dementia, myoclonus**, and cerebellar dysfunction, which differs from the gradual onset of chorea and mood changes seen here. *Neurofibrillary tangles on brain biopsy* - **Neurofibrillary tangles**, composed of hyperphosphorylated tau protein, are a hallmark pathological feature of **Alzheimer's disease**. - **Alzheimer's disease** is primarily characterized by progressive memory loss and other cognitive deficits, but typically does not present with prominent chorea as the initial motor symptom. *Frontotemporal atrophy on head CT* - **Frontotemporal atrophy** is characteristic of **frontotemporal dementia (FTD)**, which can present with behavioral changes, personality alterations, and language difficulties. - While FTD can cause psychiatric symptoms, the presence of prominent **chorea** makes Huntington's disease a more likely diagnosis.

Question 91: A 27-year-old man presents to the emergency department with dizziness. He states he has experienced a sustained sensation of the room spinning that is low grade and constant since this morning. The patient occasionally feels nauseous and has been taking diphenydramine to sleep which helps with his symptoms. The patient is generally healthy, has no other medical conditions, and only endorses eating more garlic recently to get over a cold he had a few days ago. His temperature is 98.7°F (37.1°C), blood pressure is 122/81 mmHg, pulse is 82/min, respirations are 15/min, and oxygen saturation is 99% on room air. Physical exam is notable for a healthy man. The patient is sat upright, his head is turned slightly to the right, and he is laid back flat rapidly. This does not provoke any symptoms even when repeated on the left side. A nystagmus is notable on cranial nerve exam as well as bilateral decreased hearing. The patient’s tandem gait is unstable; however, his baseline gait appears unremarkable despite the patient stating he has a sustained sensation of imbalance. Which of the following is the most likely diagnosis?

A. Labyrinthitis (Correct Answer)
B. Vertebrobasilar stroke
C. Vestibular neuritis
D. Meniere disease
E. Benign paroxysmal positional vertigo

Explanation: ***Labyrinthitis*** - The patient presents with **vertigo, nystagmus, and bilateral decreased hearing** following a recent cold, which is highly suggestive of **labyrinthitis**. - **Labyrinthitis** is typically caused by a viral infection of the inner ear, affecting both the **vestibular and cochlear functions**. *Vertebrobasilar stroke* - While a **vertebrobasilar stroke** can cause dizziness and nystagmus, it would typically present with **focal neurological deficits** such as ataxia, dysarthria, or diplopia, which are absent here. - The patient's otherwise healthy status and the history of a recent infection make a stroke less likely in this young individual. *Vestibular neuritis* - **Vestibular neuritis** presents with sudden, severe vertigo and nystagmus, but it **does not involve hearing loss**, unlike labyrinthitis. - The patient's complaint of **bilateral decreased hearing** rules out isolated vestibular neuritis. *Meniere disease* - **Meniere disease** is characterized by recurrent episodes of vertigo, fluctuating sensorineural hearing loss, tinnitus, and aural fullness. - The patient's symptoms are described as a **sustained, constant sensation of spinning** and not episodic, making Meniere disease less likely. *Benign paroxysmal positional vertigo* - **BPPV** causes brief episodes of vertigo triggered by specific head movements, and it is usually diagnosed with a **positive Dix-Hallpike test**. - The patient's symptoms are **constant and sustained**, and the **Dix-Hallpike maneuver did not provoke symptoms**, ruling out BPPV.

Question 92: A 44-year-old woman comes to her primary care physician with complaints of irritation and a gritty sensation in her eyes for the past few months. She denies any discharge from her eyes. She has no significant past medical or surgical history. She takes multivitamins occasionally but denies use of any other medication. On further questioning, she expresses her concerns about frequent dental caries for the past 2 years. On examination, her temperature is 37.1°C (98.8°F), blood pressure is 110/80 mm Hg, pulse rate is 74/min, and respiratory rate is 16/min. Which of the following is the most likely cause of her symptoms?

A. Sjögren's syndrome (Correct Answer)
B. Fibromyalgia
C. Rheumatoid arthritis
D. Systemic lupus erythematosus (SLE)
E. Scleroderma

Explanation: ***Sjögren's syndrome*** - The patient's complaints of **irritation and gritty sensation in her eyes** (suggesting **dry eyes**), along with **frequent dental caries** (suggesting **dry mouth**), are classic symptoms of **Sjögren's syndrome**, an autoimmune disorder characterized by destruction of exocrine glands. - The absence of ocular discharge further supports dry eyes rather than infection or allergy. *Fibromyalgia* - **Fibromyalgia** is characterized by widespread **musculoskeletal pain**, fatigue, and sleep disturbances. - It does not explain the specific symptoms of dry eyes and increased dental caries due to xerostomia. *Rheumatoid arthritis* - **Rheumatoid arthritis** primarily involves chronic **symmetrical polyarthritis**, particularly affecting small joints. - While it can be associated with secondary Sjögren's, the primary symptoms presented here are not joint-related. *Systemic lupus erythematosus (SLE)* - **SLE** is a systemic autoimmune disease with diverse manifestations, including joint pain, skin rashes, and kidney involvement. - While **dry eyes** can occur, **dental caries** due to dry mouth are not a primary diagnostic feature of SLE, and other SLE-specific symptoms are absent. *Scleroderma* - **Scleroderma** is characterized by **skin thickening** and fibrosis affecting various organs. - Symptoms like dry eyes and dental caries are not typical presenting features; instead, patients often experience **Raynaud's phenomenon**, dysphagia, and skin changes.

Question 93: A 47-year-old man presents to the clinic for an evaluation of intense itching of his right thigh region for the past few days. He states some ‘red bumps’ just began to form. The patient mentions that he was recently at a business conference in Miami. He has a past medical history of hypertension, diabetes type 2, and hyperlipidemia. He takes enalapril, metformin, and atorvastatin. He does not smoke or drink. His vitals are within normal limits today. On physical examination, a linear line with 3 red papules is present along the medial aspect of his right thigh. Additionally, there are small rows of bumps on his left leg and right forearm. Excoriations are also apparent in the same region. Which of the following is the most likely diagnosis?

A. Scabies
B. Bed bug bite (Correct Answer)
C. Cutaneous larva migrans
D. Flea bite
E. Spider bite

Explanation: ***Bed bug bite*** - The presence of **linear lesions** (often described as "breakfast, lunch, and dinner") and **rows of bumps** on exposed skin, especially after recent travel, is highly characteristic of **bed bug bites**. - **Intense itching** and **red papules** appearing a few days after exposure further support this diagnosis. *Scabies* - While scabies also causes intense itching and red papules, it typically presents with **serpiginous burrows** in characteristic locations such as the finger webs, wrists, and axillae. - Scabies is also more often associated with generalized pruritus rather than localized linear lesions from recent exposure. *Cutaneous larva migrans* - This condition is caused by hookworm larvae and presents with a **highly pruritic, intensely erythematous, raised, serpiginous tract** that migrates over time. - The described lesions are more consistent with bites in a linear pattern rather than a migratory burrow. *Flea bite* - Flea bites often appear as **small, red, itchy bumps** usually clustered around ankles or areas covered by tight clothing. - While itchy, they typically do not form the distinct linear "breakfast, lunch, and dinner" pattern seen with bed bugs. *Spider bite* - Most spider bites present as a **single lesion**, often with a central puncture mark, and can range from mild local reactions to necrotic lesions, depending on the spider. - Bites from multiple spiders or multiple bites in a linear pattern are highly unusual and do not fit the description of lesions in rows.

Question 94: A 25-year-old woman with a history of polycystic ovarian syndrome, depression, and chronic bilateral ear infections presents to the otolaryngologist's clinic 12 weeks after right ear tympanoplasty. Her audiology report one week prior showed that her hearing improved as expected by 20 decibels. However, she reports that she has occasional shooting pain with eating and when she wears earrings. She states that she has a stressful job as a cashier at the local department store and often sleeps poorly. She denies any neck pain or tenderness when she washes her face. On physical exam, no tenderness is elicited with preauricular or mandibular palpation bilaterally. No jaw clicking is heard. Right postauricular tapping causes tenderness in her right tonsillar area. Her molar teeth appear even and symmetric bilaterally. Her uvula is midline and her gag reflex is intact. What is the most likely diagnosis?

A. Cluster headache
B. Atypical migraine
C. Bruxism
D. Trigeminal neuralgia
E. Glossopharyngeal neuralgia (Correct Answer)

Explanation: ***Glossopharyngeal neuralgia*** - The description of **shooting pain with eating** and **referred tenderness to the tonsillar area** upon postauricular tapping (which can stimulate the glossopharyngeal nerve or C2/C3 dermatomes) strongly suggests glossopharyngeal neuralgia. - This condition is characterized by **brief, severe attacks of pain** in the ear, tonsil, posterior tongue, or pharynx, often triggered by swallowing, chewing, or touching the ear. *Cluster headache* - Cluster headaches present with **severe, unilateral pain around the eye or temple**, accompanied by autonomic symptoms like **lacrimation, rhinorrhea, ptosis, or miosis**. - They are typically **short-lived but recurrent** and do not involve shooting pain in the tonsillar area or trigger factors like eating or wearing earrings. *Atypical migraine* - Atypical migraines encompass a wide range of headache presentations, but generally involve **pulsatile pain**, often with **photophobia, phonophobia, or nausea**. - While migraines can be severe, the specific triggers of eating and wearing earrings, and the referred tonsillar pain, are not typical features. *Bruxism* - Bruxism involves **involuntary grinding or clenching of teeth**, typically during sleep, leading to **jaw pain, headaches**, and **tooth wear**. - The absence of jaw clicking or tenderness on palpation of the temporomandibular joint (TMJ) and masticatory muscles makes bruxism less likely. *Trigeminal neuralgia* - Trigeminal neuralgia causes **sudden, severe, shock-like pain** in areas supplied by the **trigeminal nerve**, often triggered by light touch, chewing, or talking. - While it can involve the ear area (V3 distribution), the characteristic **referred pain to the tonsillar area** and specific triggers point more towards glossopharyngeal neuralgia.

Question 95: A 69-year-old man presents to his primary care physician for pain when he walks. He states that the pain is the worst in his left great toe but is also present in his hips and knees. He says that his symptoms are worse with activity and tend to improve with rest. His symptoms have progressively worsened over the past several years. He has a past medical history of obesity, type II diabetes mellitus, smoking, and hypertension. He drinks roughly ten beers per day. His current medications include metformin, insulin, lisinopril, and hydrochlorothiazide. The patient has a recent travel history to Bangkok where he admits to having unprotected sex. On physical exam, examination of the lower extremity results in pain. There is crepitus of the patient's hip when his thigh is flexed and extended. Which of the following is the most likely diagnosis?

A. Pseudogout
B. Gout
C. Rheumatoid arthritis
D. Infectious arthritis
E. Osteoarthritis (Correct Answer)

Explanation: ***Osteoarthritis*** - The patient presents with classic features of **osteoarthritis (OA)**: **progressive worsening over several years**, pain that is **worse with activity and improves with rest** (mechanical pain pattern), and **crepitus of the hip** on examination. - **Crepitus** is a hallmark physical finding in OA, indicating cartilage degradation and bone-on-bone contact. - The patient has major risk factors including **age (69 years)**, **obesity**, and involvement of **weight-bearing joints** (hips and knees). - While the great toe is also affected, polyarticular OA commonly involves multiple joints including the first metatarsophalangeal joint. *Gout* - Although the patient has risk factors for gout (**alcohol consumption** and **thiazide diuretic use**), gout typically presents with **acute, severe attacks** of monoarticular arthritis, not chronic progressive pain over several years. - Acute gout would present with sudden onset of severe pain, erythema, warmth, and swelling, which are not described in this case. - The **mechanical pain pattern** (worse with activity, better with rest) and **crepitus** are inconsistent with gout. *Pseudogout* - Pseudogout (calcium pyrophosphate deposition disease) typically causes **acute attacks** affecting larger joints like the knees, similar to gout. - The **chronic progressive nature** of this patient's symptoms over several years, along with crepitus, is not consistent with pseudogout. - Pseudogout does not explain the mechanical pain pattern or the hip crepitus. *Infectious arthritis* - While the patient's recent travel and unprotected sex raise concern for sexually transmitted infections, **septic arthritis** would present with **acute onset**, severe pain, fever, warmth, erythema, and systemic signs of infection. - The **chronic progressive course over several years** is completely inconsistent with infectious arthritis. - Gonococcal arthritis can cause migratory polyarthritis but would be acute, not chronic. *Rheumatoid arthritis* - Rheumatoid arthritis typically presents with **symmetric polyarthritis** affecting small joints of the hands and feet, with **prolonged morning stiffness** (>30-60 minutes). - The pain pattern in RA is **inflammatory** (worse with rest, improves with activity), which is the **opposite** of this patient's presentation. - **Crepitus** and mechanical pain pattern point to a degenerative process (OA), not an inflammatory arthropathy like RA.

Question 96: A 25-year-old male patient presents to your clinic in significant distress. He states he has excruciating, stabbing pain around the left side of his head, and his left eye will not stop tearing. These types of headaches have been occurring for the past week every morning when he awakens and last around 60 minutes. He denies any aura, nausea, or vomiting. He denies any other past medical history. What is this patient's diagnosis?

A. Cluster headache (Correct Answer)
B. Trigeminal neuralgia
C. Migraine headache
D. Short-lasting unilateral neuralgiform headaches with conjunctival injection and tearing (SUNCT) syndrome
E. Chronic paroxysmal hemicrania (CPH)

Explanation: ***Cluster headache*** - This patient's symptoms are classic for a cluster headache: **excruciating unilateral pain** around the orbit, **lacrimation** (tearing), and a **circadian rhythm** (occurring at a similar time each day, often upon awakening). - The **brief duration** (60 minutes) and the absence of aura, nausea, or vomiting further support this diagnosis. *Trigeminal neuralgia* - Characterized by **sudden, severe, electric shock-like facial pain** along the distribution of the trigeminal nerve, often triggered by touch or movement. - While the pain is severe and unilateral, it typically involves the face and not specifically orbital tearing, and the duration is usually seconds to minutes, not an hour. *Migraine headache* - Migraines are typically associated with **pulsating pain**, often unilateral, and accompanied by **nausea, vomiting, photophobia, and phonophobia**. - Although unilateral, the described tearing, stabbing pain, and short duration without associated symptoms like nausea or vomiting make migraine less likely. *Short-lasting unilateral neuralgiform headaches with conjunctival injection and tearing (SUNCT) syndrome* - SUNCT is characterized by **very frequent (up to 200 times a day), short-duration (5-240 seconds) jabs of unilateral pain** with prominent autonomic features like conjunctival injection and tearing. - The duration of the attacks (60 minutes) in this patient is too long for SUNCT syndrome. *Chronic paroxysmal hemicrania (CPH)* - CPH involves **frequent (5-40 per day), moderate to severe unilateral pain attacks** lasting 2-45 minutes, associated with autonomic symptoms. - A key differentiating feature is its **absolute responsiveness to indomethacin**, and while similar to cluster, the attacks are typically shorter and more frequent than described here.

Question 97: A 30-year-old woman comes to the physician because of a swelling on her neck for 5 months. It has gradually enlarged in size and is mildly painful. She has also had intermittent episodes of throbbing headache, sweating, and palpitations over the past 3 months. Menses occur at regular 28-day intervals and last for 4–5 days. She does not smoke, occasionally consumes alcohol on weekends. She appears thin and pale. Her temperature is 38.7°C (101.7°F), pulse is 112/min, and blood pressure is 140/90 mm Hg. Examination shows a firm, 3-cm swelling on the neck that moves with swallowing; there is no lymphadenopathy. Cardiopulmonary examination shows no abnormalities. Laboratory studies show: Hemoglobin 13 g/dL Leukocyte count 9500/mm3 Platelet count 230,000/mm3 Serum Na+ 136 mEq/L K+ 3.5 mEq/L Cl- 104 mEq/L TSH 2.3 μU/mL Calcitonin 300 ng/dL (Normal < 5 ng/dL) An electrocardiogram shows sinus tachycardia. Which of the following laboratory abnormalities is most likely to be seen?

A. Increased serum gastrin
B. Increased serum cortisol
C. Increased serum T3 levels
D. Increased urinary 5-HIAA
E. Increased plasma metanephrines (Correct Answer)

Explanation: ***Increased plasma metanephrines*** - The patient's symptoms of **throbbing headache, sweating, and palpitations**, along with **hypertension and tachycardia**, are highly suggestive of a **pheochromocytoma**. - **Plasma metanephrines** (metanephrine and normetanephrine) are metabolites of catecholamines and are the most sensitive and specific biochemical tests for diagnosing pheochromocytoma. *Increased serum gastrin* - **Increased serum gastrin** is associated with **Zollinger-Ellison syndrome**, which causes severe peptic ulcer disease and diarrhea. These symptoms are not present in this patient. - While neuroendocrine tumors can produce gastrin, the patient's primary symptoms point to catecholamine excess. *Increased serum cortisol* - **Increased serum cortisol** is characteristic of **Cushing's syndrome**, which presents with central obesity, moon facies, buffalo hump, and striae, none of which are described. - The patient's thin appearance and other symptoms are inconsistent with hypercortisolism. *Increased serum T3 levels* - **Increased serum T3 levels** indicate hyperthyroidism, which could explain tachycardia and weight loss, but the **TSH is normal** (2.3 μU/mL). - The elevated calcitonin and the specific paroxysmal symptoms like throbbing headaches and sweating are not typical for hyperthyroidism. *Increased urinary 5-HIAA* - **Increased urinary 5-HIAA** (5-hydroxyindoleacetic acid) is a marker for **carcinoid syndrome**, which typically presents with flushing, diarrhea, bronchospasm, and valvular heart disease. - These symptoms are not consistent with the patient's presentation, and the elevated calcitonin points to a different neuroendocrine origin.

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