A 41-year-old man presents to the emergency department because of brownish discoloration of his urine for the last several days. The review of symptoms includes complaints of increasing abdominal girth, early satiety, and difficulty breathing on exertion. The past medical history includes essential hypertension for 19 years. The medication list includes lisinopril and hydrochlorothiazide. He had a right inguinal hernia repair when he was a teenager. He smokes 20–30 cigarettes daily for the last 21 years, and drinks alcohol socially. His father died of a hemorrhagic stroke at the age of 69 years. The vital signs include: temperature 37.0°C (98.6°F), blood pressure 131/88 mm Hg, and pulse 82/min. The physical examination is positive for a palpable right upper quadrant mass. The abdominal ultrasound shows multiple bilateral kidney cysts and hepatic cysts. Which of the following is the most likely diagnosis?
Q242
A 75-year-old man comes to the physician because of a 3-month history of upper abdominal pain, nausea, and sensation of early satiety. He has also had a 9.4-kg (20.7-lb) weight loss over the past 4 months. He has osteoarthritis. He drinks two beers every night with dinner. His only medication is ibuprofen. Esophagogastroduodenoscopy shows an ulcerated mass in the lesser curvature of the stomach. A biopsy specimen obtained during endoscopy shows irregular-shaped tubules with intraluminal mucus and debris. Which of the following is the most likely predisposing factor for this patient's condition?
Q243
A 72-year-old male with a past medical history significant for aortic stenosis and hypertension presents to the emergency department complaining of weakness for the past 3 weeks. He states that, apart from feeling weaker, he also has noted lightheadedness, pallor, and blood-streaked stools. The patient's vital signs are stable, and he is in no acute distress. Laboratory workup reveals that the patient is anemic. Fecal occult blood test is positive for bleeding. EGD was performed and did not reveal upper GI bleeding. Suspecting a lower GI bleed, a colonoscopy is performed after prepping the patient, and it is unremarkable. What would be an appropriate next step for localizing a lower GI bleed in this patient?
Q244
A 53-year-old woman is brought to the emergency department because of an episode of lightheadedness and left arm weakness for the last hour. Her symptoms were preceded by tremors, palpitations, and diaphoresis. During the past 3 months, she has had increased appetite and has gained 6.8 kg (15 lbs). She has hypertension, hyperlipidemia, anxiety disorder, and gastroesophageal reflux. She works as a nurse in an ICU and has been under more stress than usual. She does not smoke. She drinks 5 glasses of wine every week. Current medications include enalapril, atorvastatin, fluoxetine, and omeprazole. She is 168 cm (5 ft 6 in) tall and weighs 100 kg (220 lb); BMI is 36 kg/m2. Her temperature is 37°C (98.8°F), pulse is 78/min, and blood pressure is 130/80 mm Hg. Cardiopulmonary examination shows no abnormalities. The abdomen is soft and nontender. Fasting serum studies show:
Na+ 140 mEq/L
K+ 3.5 mEq/L
HCO3- 22 mEq/L
Creatinine 0.8 mg/dL
Glucose 37 mg/dL
Insulin 280 μU/mL (N=11–240)
Thyroid-stimulating hormone 2.8 μU/mL
C-peptide 4.9 ng/mL (N=0.8–3.1)
Urine screen for sulfonylurea is negative. Which of the following is the most likely diagnosis?
Q245
A 28-year-old man presents with one week of redness and discharge in his eyes, pain and swelling in his left second and third toes, and rash on the soles of his feet. He is sexually active with multiple partners and uses condoms occasionally. He denies any recent travel or illness and does not take any medications. Review of systems is otherwise unremarkable. On physical exam, he has bilateral conjunctivitis, dactylitis of the left second and third toes, and crusty yellow-brown vesicles on his plantar feet. Complete blood count and chemistries are within normal limits. Erythrocyte sedimentation rate (ESR) is 40 mm/h. Toe radiographs demonstrate soft tissue swelling but no fractures. Which diagnostic test should be performed next?
Q246
A 32-year-old man presents to the clinic with a dull low back pain radiating to the buttocks. He first noted it about 2 years ago and it has progressed since then. He notes that it is worse in the morning and improves later in the day after physical activity. The patient also reports morning stiffness lasting up to 30 minutes and blurred vision, which started about 7 months ago. The patient's vital signs include: blood pressure 130/80 mm Hg, heart rate 88/min, respiratory rate 16/min, and temperature 36.8°C (98.2°F). Physical examination reveals tenderness over the sacroiliac joints and limitation of the lumbar spine movements in the sagittal plane. The patient's X-ray is shown in the picture below. Which of the following HLA variants is associated with this patient's condition?
Q247
A 45-year-old man presents to his primary care physician because of abdominal pain. He has had this pain intermittently for several years but feels that it has gotten worse after he started a low carbohydrate diet. He says that the pain is most prominent in the epigastric region and is also associated with constipation and foul smelling stools that float in the toilet bowl. He has a 15-year history of severe alcoholism but quit drinking 1 year ago. Laboratory studies are obtained showing a normal serum amylase and lipase. Both serum and urine toxicology are negative. His physician starts him on appropriate therapy and checks to make sure that his vitamin and mineral levels are appropriate. Which of the following deficiency syndromes is most closely associated with the cause of this patient's abdominal pain?
Q248
A 60-year-old man has had intermittent pain in his right great toe for the past 2 years. Joint aspiration and crystal analysis shows thin, tapered, needle shaped intracellular crystals that are strongly negatively birefringent. Radiograph demonstrates joint space narrowing of the 1st metatarsophalangeal (MTP) joint with medial soft tissue swelling. What is the most likely cause of this condition?
Q249
A 67-year-old woman presents to the clinic with a 9-month history of seeing bright red blood in the toilet after defecating. Additional complaints include fatigue, shortness of breath, and mild lethargy. She denies the loss of weight, abdominal pain, or changes in dietary behavior. She consumes a balanced diet and takes multiple vitamins every day. The current vital signs include the following: temperature is 37.0°C (98.6°F), pulse rate is 68/min, blood pressure is 130/81 mm Hg, and the respiratory rate is 13/min. On physical examination, you notice increased capillary refill time and pale mucosa. What are the most likely findings for hemoglobin, hematocrit, red blood cell count, and mean corpuscular volume?
Q250
A 35-year-old woman presents for evaluation of symmetric proximal muscle weakness. The patient also presents with a blue-purple discoloration of the upper eyelids accompanied by rashes on the knuckles, as shown in the picture below. What is the most likely cause?
Gastroenterology US Medical PG Practice Questions and MCQs
Question 241: A 41-year-old man presents to the emergency department because of brownish discoloration of his urine for the last several days. The review of symptoms includes complaints of increasing abdominal girth, early satiety, and difficulty breathing on exertion. The past medical history includes essential hypertension for 19 years. The medication list includes lisinopril and hydrochlorothiazide. He had a right inguinal hernia repair when he was a teenager. He smokes 20–30 cigarettes daily for the last 21 years, and drinks alcohol socially. His father died of a hemorrhagic stroke at the age of 69 years. The vital signs include: temperature 37.0°C (98.6°F), blood pressure 131/88 mm Hg, and pulse 82/min. The physical examination is positive for a palpable right upper quadrant mass. The abdominal ultrasound shows multiple bilateral kidney cysts and hepatic cysts. Which of the following is the most likely diagnosis?
A. Simple kidney cyst
B. Renal cell carcinoma
C. Medullary sponge kidney
D. Autosomal dominant polycystic kidney disease (Correct Answer)
E. Von Hippel-Lindau syndrome
Explanation: ***Autosomal dominant polycystic kidney disease***
- The presence of **multiple bilateral kidney cysts** and **hepatic cysts**, along with symptoms like **increasing abdominal girth**, **early satiety**, and **hypertension** in a 41-year-old man, is highly characteristic of **autosomal dominant polycystic kidney disease (ADPKD)**.
- The **brownish discoloration of urine** suggests potential bleeding into a cyst or a urinary tract infection, common complications of ADPKD.
*Simple kidney cyst*
- A simple kidney cyst is typically **solitary, unilateral**, and usually asymptomatic.
- It does not explain the **multiplicity of cysts**, **bilateral involvement**, the presence of hepatic cysts, or the associated systemic symptoms.
*Renal cell carcinoma*
- While renal cell carcinoma can present with a palpable mass and hematuria (brownish urine), it typically manifests as a **single, solid mass** rather than **multiple bilateral cystic lesions**.
- Renal cell carcinoma is not associated with widespread hepatic cysts as seen in this patient.
*Medullary sponge kidney*
- This condition involves **dilation of the collecting ducts** in the renal pyramids and is often asymptomatic, though it can lead to **recurrent kidney stones** and urinary tract infections.
- It presents with **normal renal cortex** and does not typically involve multiple large cysts or hepatic cysts.
*Von Hippel-Lindau syndrome*
- This genetic disorder is characterized by the development of **cysts and tumors** in various organs, including the kidneys (**renal cell carcinoma**), pancreas, and central nervous system.
- While it can cause renal cysts, the primary renal manifestation is often **clear cell renal cell carcinoma**, and the clinical picture in this patient, particularly the widespread hepatic cysts and the absence of other typical VHL findings, makes it less likely than ADPKD.
Question 242: A 75-year-old man comes to the physician because of a 3-month history of upper abdominal pain, nausea, and sensation of early satiety. He has also had a 9.4-kg (20.7-lb) weight loss over the past 4 months. He has osteoarthritis. He drinks two beers every night with dinner. His only medication is ibuprofen. Esophagogastroduodenoscopy shows an ulcerated mass in the lesser curvature of the stomach. A biopsy specimen obtained during endoscopy shows irregular-shaped tubules with intraluminal mucus and debris. Which of the following is the most likely predisposing factor for this patient's condition?
A. Low-fiber diet
B. NSAID use
C. Inflammatory bowel disease
D. Blood type O
E. Dietary nitrates (Correct Answer)
Explanation: ***Dietary nitrates***
- High dietary intake of **nitrates and nitrites**, commonly found in processed meats, smoked foods, and certain preserved foods, is an established risk factor for **gastric adenocarcinoma**
- Nitrates are converted to **N-nitroso compounds** in the stomach, which are potent carcinogens that damage gastric epithelial DNA
- The histologic finding of **irregular tubules with intraluminal mucus** is consistent with intestinal-type gastric adenocarcinoma, which has strong epidemiologic associations with dietary carcinogens
- Among the options provided, dietary nitrates represent the most evidence-based predisposing factor for gastric cancer development
*NSAID use*
- While chronic **NSAID use** (ibuprofen) is a major risk factor for **peptic ulcer disease** and can cause gastric ulcers, it is **NOT an established risk factor** for gastric adenocarcinoma
- NSAIDs cause mucosal injury through COX-1 inhibition and reduced prostaglandin synthesis, leading to ulceration but not malignant transformation
- Some studies suggest NSAIDs may actually have a **protective effect** against certain GI malignancies through COX-2 inhibition
- The patient's chronic NSAID use may explain gastric symptoms but does not predispose to the adenocarcinoma itself
*Low-fiber diet*
- A **low-fiber diet** is associated with increased risk of **colorectal cancer** and diverticular disease, not gastric malignancy
- No strong epidemiologic evidence links low dietary fiber to gastric adenocarcinoma development
- This is not a recognized risk factor for the patient's condition
*Inflammatory bowel disease*
- **IBD** (Crohn's disease and ulcerative colitis) primarily affects the intestines and is a risk factor for **colorectal adenocarcinoma**, not gastric cancer
- The stomach is rarely the primary site of involvement in IBD
- This patient's presentation with a gastric mass does not suggest IBD-related pathology
*Blood type O*
- **Blood type A** (not type O) is associated with increased risk of gastric adenocarcinoma, likely due to enhanced susceptibility to **H. pylori** colonization and altered gastric mucin composition
- **Blood type O** is actually considered relatively **protective** against gastric cancer compared to type A
- This option represents the opposite relationship to gastric cancer risk
Question 243: A 72-year-old male with a past medical history significant for aortic stenosis and hypertension presents to the emergency department complaining of weakness for the past 3 weeks. He states that, apart from feeling weaker, he also has noted lightheadedness, pallor, and blood-streaked stools. The patient's vital signs are stable, and he is in no acute distress. Laboratory workup reveals that the patient is anemic. Fecal occult blood test is positive for bleeding. EGD was performed and did not reveal upper GI bleeding. Suspecting a lower GI bleed, a colonoscopy is performed after prepping the patient, and it is unremarkable. What would be an appropriate next step for localizing a lower GI bleed in this patient?
A. Technetium-99 labelled erythrocyte scintigraphy (Correct Answer)
B. Flexible sigmoidoscopy
C. Nasogastric tube lavage
D. Ultrasound of the abdomen
E. CT of the abdomen
Explanation: ***Technetium-99 labelled erythrocyte scintigraphy***
- This test can detect **slow-rate lower GI bleeds** (as low as 0.2-0.5 mL/min) that may be missed by endoscopy or colonoscopy, especially when the bleeding is intermittent or subtle.
- Given the **negative EGD** and **unremarkable colonoscopy** despite evidence of an ongoing lower GI bleed, this nuclear medicine study is appropriate for localization.
- Particularly useful in this patient with **aortic stenosis**, where angiodysplasia (vascular malformations, often in the small bowel) is a common cause of obscure GI bleeding (Heyde's syndrome).
*Flexible sigmoidoscopy*
- This procedure only visualizes the **rectum and a portion of the sigmoid colon**, which is insufficient given the negative full colonoscopy.
- It would not provide any new information for localizing a bleed that has already been ruled out from the accessible colon.
*Nasogastric tube lavage*
- This procedure is used to assess for **upper GI bleeding** by checking for blood in the gastric contents.
- The EGD already ruled out an upper GI bleed, making this step unnecessary and unhelpful for a suspected lower GI source.
*Ultrasound of the abdomen*
- Abdominal ultrasound is primarily used to evaluate **solid organs** (e.g., liver, gallbladder, kidneys) and potential fluid collections.
- It is generally **not effective** for localizing or diagnosing the source of active GI bleeding.
*CT of the abdomen*
- A standard CT abdomen without specialized imaging protocol has **limited sensitivity** for detecting the source of GI bleeding.
- While **CT angiography** (a different test with IV contrast timed to arterial phase) can detect active bleeding at rates >0.3-0.5 mL/min, a routine "CT of the abdomen" as listed in this option would not be adequate for localizing occult GI bleeding.
Question 244: A 53-year-old woman is brought to the emergency department because of an episode of lightheadedness and left arm weakness for the last hour. Her symptoms were preceded by tremors, palpitations, and diaphoresis. During the past 3 months, she has had increased appetite and has gained 6.8 kg (15 lbs). She has hypertension, hyperlipidemia, anxiety disorder, and gastroesophageal reflux. She works as a nurse in an ICU and has been under more stress than usual. She does not smoke. She drinks 5 glasses of wine every week. Current medications include enalapril, atorvastatin, fluoxetine, and omeprazole. She is 168 cm (5 ft 6 in) tall and weighs 100 kg (220 lb); BMI is 36 kg/m2. Her temperature is 37°C (98.8°F), pulse is 78/min, and blood pressure is 130/80 mm Hg. Cardiopulmonary examination shows no abnormalities. The abdomen is soft and nontender. Fasting serum studies show:
Na+ 140 mEq/L
K+ 3.5 mEq/L
HCO3- 22 mEq/L
Creatinine 0.8 mg/dL
Glucose 37 mg/dL
Insulin 280 μU/mL (N=11–240)
Thyroid-stimulating hormone 2.8 μU/mL
C-peptide 4.9 ng/mL (N=0.8–3.1)
Urine screen for sulfonylurea is negative. Which of the following is the most likely diagnosis?
A. Binge eating disorder
B. Insulinoma (Correct Answer)
C. Cushing's syndrome
D. Exogenous hypoglycemia
E. Polycystic ovarian syndrome
Explanation: ***Insulinoma***
- This patient presents with **Whipple's triad** (symptoms of hypoglycemia, a low plasma glucose level, and resolution of symptoms after glucose administration), high **insulin**, and high **C-peptide** levels.
- The elevated **C-peptide** distinguishes it from exogenous insulin administration, and the negative sulfonylurea screen rules out drug-induced hypoglycemia.
*Binge eating disorder*
- Characterized by recurrent episodes of **eating an unusually large amount of food** in a short period with a sense of **loss of control**, which is not the primary presentation here.
- While the patient has gained weight and has an increased appetite, binge eating disorder does not directly explain the episodes of **hypoglycemia** and associated symptoms like lightheadedness and weakness.
*Cushing's syndrome*
- Presents with symptoms like **central obesity, moon facies, buffalo hump, and striae**, and typically causes **hyperglycemia**, not hypoglycemia.
- Labs would show **elevated cortisol levels**, not the low glucose and high insulin/C-peptide seen here.
*Exogenous hypoglycemia*
- This would result from administration of **insulin** or **sulfonylureas**, leading to high insulin but **low C-peptide** (if exogenous insulin) or a **positive sulfonylurea screen**.
- The patient's **high C-peptide** and negative sulfonylurea screen rule out exogenous causes.
*Polycystic ovarian syndrome*
- Characterized by **menstrual irregularities, hyperandrogenism, and polycystic ovaries** on ultrasound.
- While it is associated with **insulin resistance** and obesity, it does not typically cause acute symptomatic hypoglycemia with elevated insulin and C-peptide as seen.
Question 245: A 28-year-old man presents with one week of redness and discharge in his eyes, pain and swelling in his left second and third toes, and rash on the soles of his feet. He is sexually active with multiple partners and uses condoms occasionally. He denies any recent travel or illness and does not take any medications. Review of systems is otherwise unremarkable. On physical exam, he has bilateral conjunctivitis, dactylitis of the left second and third toes, and crusty yellow-brown vesicles on his plantar feet. Complete blood count and chemistries are within normal limits. Erythrocyte sedimentation rate (ESR) is 40 mm/h. Toe radiographs demonstrate soft tissue swelling but no fractures. Which diagnostic test should be performed next?
A. Rheumatoid factor
B. Anti-cyclic citrullinated peptide antibody assay
C. HLA-B27
D. Nucleic acid amplification testing for Chlamydia trachomatis (Correct Answer)
E. Antinuclear antibody assay
Explanation: ***Nucleic acid amplification testing for Chlamydia trachomatis***
- The patient's symptoms (conjunctivitis, dactylitis, and plantar rash) with a history of unprotected sexual activity are highly suggestive of **reactive arthritis**, often triggered by **Chlamydia trachomatis infection**.
- **NAAT** is the most sensitive and specific test for detecting *Chlamydia trachomatis* in urethral or urine samples, even in asymptomatic infections.
*Rheumatoid factor*
- This test is primarily used for **rheumatoid arthritis**, which typically presents with symmetric polyarthritis, not the asymmetric dactylitis and conjunctivitis seen here.
- The patient’s acute presentation and specific rash are inconsistent with classic rheumatoid arthritis.
*Anti-cyclic citrullinated peptide antibody assay*
- Like rheumatoid factor, this assay is a specific marker for **rheumatoid arthritis** and would not be the most appropriate first step in diagnosing reactive arthritis.
- Its utility in this clinical context is minimal given the patient's symptoms point away from rheumatoid arthritis.
*HLA-B27*
- While **HLA-B27** is associated with reactive arthritis (and other spondyloarthropathies), it is a **genetic predisposition factor**, not a diagnostic test for acute infection.
- A positive result would confirm susceptibility but would not identify the underlying *Chlamydia* infection that needs treatment.
*Antinuclear antibody assay*
- This assay is used to screen for **systemic lupus erythematosus** and other autoimmune connective tissue diseases.
- The patient's acute presentation of conjunctivitis, dactylitis, and plantar rash is not typical for lupus or similar conditions.
Question 246: A 32-year-old man presents to the clinic with a dull low back pain radiating to the buttocks. He first noted it about 2 years ago and it has progressed since then. He notes that it is worse in the morning and improves later in the day after physical activity. The patient also reports morning stiffness lasting up to 30 minutes and blurred vision, which started about 7 months ago. The patient's vital signs include: blood pressure 130/80 mm Hg, heart rate 88/min, respiratory rate 16/min, and temperature 36.8°C (98.2°F). Physical examination reveals tenderness over the sacroiliac joints and limitation of the lumbar spine movements in the sagittal plane. The patient's X-ray is shown in the picture below. Which of the following HLA variants is associated with this patient's condition?
A. HLA-B27 (Correct Answer)
B. HLA-DQ2
C. HLA-DR3
D. HLA-B47
E. HLA-DR4
Explanation: ***HLA-B27***
- The clinical presentation of **dull low back pain**, morning stiffness improving with activity, and **blurred vision** (suggestive of uveitis) points to a spondyloarthropathy, most commonly **ankylosing spondylitis**.
- **HLA-B27** is a strong genetic risk factor and is present in a high percentage of patients with ankylosing spondylitis and other spondyloarthropathies, making it the most likely associated HLA variant.
*HLA-DQ2*
- **HLA-DQ2** is primarily associated with **celiac disease**, an autoimmune disorder affecting the small intestine, and has no direct linkage to spondyloarthropathies.
- The patient's symptoms are musculoskeletal and ocular, not gastrointestinal, which rules out celiac disease.
*HLA-DR3*
- **HLA-DR3** is associated with various autoimmune conditions such as **Type 1 Diabetes**, **Graves' disease**, and **Sjogren's syndrome**, none of which align with the patient's symptoms.
- There is no known direct association between HLA-DR3 and spondyloarthropathies or uveitis.
*HLA-B47*
- **HLA-B47** is primarily associated with **21-hydroxylase deficiency**, a form of congenital adrenal hyperplasia, and it has no relevance to the patient's musculoskeletal and ocular symptoms.
- This genetic marker is not linked to inflammatory joint diseases or uveitis.
*HLA-DR4*
- **HLA-DR4** is a significant genetic marker for **rheumatoid arthritis** and certain other autoimmune disorders.
- The patient's symptoms (back pain improving with activity, sacroiliac tenderness, uveitis) are not typical for rheumatoid arthritis, which usually affects peripheral joints and worsens with activity.
Question 247: A 45-year-old man presents to his primary care physician because of abdominal pain. He has had this pain intermittently for several years but feels that it has gotten worse after he started a low carbohydrate diet. He says that the pain is most prominent in the epigastric region and is also associated with constipation and foul smelling stools that float in the toilet bowl. He has a 15-year history of severe alcoholism but quit drinking 1 year ago. Laboratory studies are obtained showing a normal serum amylase and lipase. Both serum and urine toxicology are negative. His physician starts him on appropriate therapy and checks to make sure that his vitamin and mineral levels are appropriate. Which of the following deficiency syndromes is most closely associated with the cause of this patient's abdominal pain?
A. Microcytic anemia
B. Megaloblastic anemia without neurologic changes
C. Cheilosis and corneal vascularization
D. Encephalopathy, ophthalmoplegia, and gait ataxia (Correct Answer)
E. Osteomalacia
Explanation: ***Encephalopathy, ophthalmoplegia, and gait ataxia***
- This triad describes **Wernicke encephalopathy**, caused by **thiamine (vitamin B1) deficiency**.
- The patient has a **15-year history of severe alcoholism**, which is the **cause** of his chronic pancreatitis and the primary risk factor for thiamine deficiency.
- **Chronic alcoholism** leads to thiamine deficiency through multiple mechanisms: poor dietary intake, impaired absorption, decreased hepatic storage, and impaired conversion to active form.
- Thiamine deficiency is the deficiency syndrome **most closely associated with the cause** (chronic alcoholism) of this patient's abdominal pain from chronic pancreatitis.
*Osteomalacia*
- Osteomalacia results from **vitamin D deficiency** due to malabsorption of fat-soluble vitamins (A, D, E, K).
- The patient has steatorrhea (foul-smelling, floating stools) indicating fat malabsorption from pancreatic exocrine insufficiency.
- While this is a **consequence** of chronic pancreatitis, it is not directly associated with the **cause** (alcoholism) of the condition.
*Microcytic anemia*
- **Microcytic anemia** is typically caused by **iron deficiency**, often from chronic blood loss.
- While malabsorption can contribute to iron deficiency, this is not the primary deficiency syndrome associated with chronic alcoholism or chronic pancreatitis.
*Megaloblastic anemia without neurologic changes*
- This describes **folate (vitamin B9) deficiency**, which is common in alcoholics due to poor nutrition and impaired absorption.
- However, folate deficiency is less specifically associated with alcoholism compared to thiamine deficiency, and it is not the most characteristic deficiency syndrome in this clinical context.
*Cheilosis and corneal vascularization*
- These symptoms are characteristic of **riboflavin (vitamin B2) deficiency**.
- While general malnutrition can occur with alcoholism and malabsorption, riboflavin deficiency is not the most prominent or characteristic deficiency associated with chronic alcoholism.
Question 248: A 60-year-old man has had intermittent pain in his right great toe for the past 2 years. Joint aspiration and crystal analysis shows thin, tapered, needle shaped intracellular crystals that are strongly negatively birefringent. Radiograph demonstrates joint space narrowing of the 1st metatarsophalangeal (MTP) joint with medial soft tissue swelling. What is the most likely cause of this condition?
A. Tuberculosis
B. Monosodium urate crystal deposition (Correct Answer)
C. Calcium pyrophosphate deposition
D. Rheumatoid arthritis
E. Septic arthritis
Explanation: ***Monosodium urate crystal deposition***
- The presence of **thin, tapered, needle-shaped intracellular crystals** that are **strongly negatively birefringent** on joint fluid analysis is pathognomonic for **gout**, caused by monosodium urate crystal deposition.
- Intermittent pain in the **first metatarsophalangeal (MTP) joint** (podagra) and medial soft tissue swelling are classic clinical findings associated with gout.
*Tuberculosis*
- Tuberculosis of a joint typically presents with **chronic pain and swelling**, often with osteolytic lesions, but not with characteristic crystal findings.
- Joint fluid analysis would show **acid-fast bacilli** or granulomatous inflammation, not birefringent crystals.
*Calcium pyrophosphate deposition*
- This condition (pseudogout) involves **rhomboid-shaped crystals** that are **weakly positively birefringent**, not needle-shaped and strongly negatively birefringent.
- Pseudogout more commonly affects larger joints like the knee and wrist, not typically the great toe MTP joint as the primary site.
*Rheumatoid arthritis*
- Rheumatoid arthritis is an **inflammatory polyarthritis** primarily affecting small joints of the hands and feet symmetrically, and does not involve crystal deposition.
- Joint fluid analysis would show inflammatory changes but not specific crystals, and serology for **rheumatoid factor** and **anti-CCP antibodies** would be positive.
*Septic arthritis*
- Septic arthritis presents with acute onset of severe joint pain, swelling, warmth, and restricted range of motion, often with **fever** and elevated inflammatory markers.
- Joint fluid analysis would show **markedly elevated white blood cell count** (typically >50,000 cells/μL with neutrophil predominance) and positive Gram stain or culture, not birefringent crystals.
- The **intermittent nature** over 2 years and crystal findings rule out acute infection.
Question 249: A 67-year-old woman presents to the clinic with a 9-month history of seeing bright red blood in the toilet after defecating. Additional complaints include fatigue, shortness of breath, and mild lethargy. She denies the loss of weight, abdominal pain, or changes in dietary behavior. She consumes a balanced diet and takes multiple vitamins every day. The current vital signs include the following: temperature is 37.0°C (98.6°F), pulse rate is 68/min, blood pressure is 130/81 mm Hg, and the respiratory rate is 13/min. On physical examination, you notice increased capillary refill time and pale mucosa. What are the most likely findings for hemoglobin, hematocrit, red blood cell count, and mean corpuscular volume?
A. Hemoglobin: ↓, hematocrit: ↓, red blood cell count: ↓, mean corpuscular volume: ↓ (Correct Answer)
B. Hemoglobin: ↑, hematocrit: ↑, red blood cell count: ↑, mean corpuscular volume: ↑
C. Hemoglobin: ↑, hematocrit: ↓, red blood cell count: ↓, mean corpuscular volume: ↑
D. Hemoglobin: ↓, hematocrit: ↓, red blood cell count: ↑, mean corpuscular volume: ↑
E. Hemoglobin: ↓, hematocrit: ↑, red blood cell count: ↓, mean corpuscular volume: ↑
Explanation: ***Hemoglobin: ↓, hematocrit: ↓, red blood cell count: ↓, mean corpuscular volume: ↓***
- This patient presents with **bright red blood per rectum**, fatigue, shortness of breath, and lethargy, along with pale mucosa and increased capillary refill time, all classic signs of **iron deficiency anemia** due to chronic blood loss.
- Iron deficiency anemia is typically a **microcytic hypochromic anemia**, characterized by decreased hemoglobin, hematocrit, red blood cell count, and a decreased mean corpuscular volume (MCV).
*Hemoglobin: ↑, hematocrit: ↑, red blood cell count: ↑, mean corpuscular volume: ↑*
- An increase in all these parameters would suggest **polycythemia**, which is an excess of red blood cells, or **macrocytic anemia** if MCV is increased, which contradicts the patient's symptoms of anemia and chronic blood loss.
- The patient's symptoms of fatigue and shortness of breath are indicative of anemia, not polycythemia.
*Hemoglobin: ↑, hematocrit: ↓, red blood cell count: ↓, mean corpuscular volume: ↑*
- This combination is inconsistent as an increase in hemoglobin generally correlates with increased hematocrit and red blood cell count, unless there's an issue with a single parameter like in **hemoconcentration**.
- A decreased hematocrit and red blood cell count with increased MCV would suggest **macrocytic anemia**, but with elevated hemoglobin this is highly unlikely.
*Hemoglobin: ↓, hematocrit: ↓, red blood cell count: ↑, mean corpuscular volume: ↑*
- While hemoglobin and hematocrit are decreased, an **increased red blood cell count** with **increased MCV** is contradictory in general and does not fit the typical profile of iron deficiency anemia.
- An increased MCV points towards **macrocytic anemia**, which is not the expected finding in chronic blood loss.
*Hemoglobin: ↓, hematocrit: ↑, red blood cell count: ↓, mean corpuscular volume: ↑*
- This combination is highly unlikely; a decreased hemoglobin and red blood cell count would typically be accompanied by a decreased hematocrit, not an increased one.
- An increased MCV indicates **macrocytic anemia**, which would not be seen with an increased hematocrit as shown in this option.
Question 250: A 35-year-old woman presents for evaluation of symmetric proximal muscle weakness. The patient also presents with a blue-purple discoloration of the upper eyelids accompanied by rashes on the knuckles, as shown in the picture below. What is the most likely cause?
A. Dermatomyositis (Correct Answer)
B. Inclusion body myositis
C. Duchenne muscular dystrophy
D. Polymyositis
E. Hypothyroidism
Explanation: ***Dermatomyositis***
- This condition is characterized by **symmetric proximal muscle weakness** accompanied by distinctive skin manifestations, such as a **heliotrope rash** (blue-purple discoloration of the upper eyelids) and **Gottron's papules** (rashes on the knuckles).
- These classic features are almost pathognomonic for dermatomyositis, an **autoimmune inflammatory myopathy**.
*Inclusion body myositis*
- Inclusion body myositis typically presents with **asymmetric distal muscle weakness** and **atrophy**, a pattern different from the symmetric proximal weakness described.
- It primarily affects older individuals and does **not involve skin manifestations**.
*Duchenne muscular dystrophy*
- This is a **genetic disorder** primarily affecting young boys, presenting with progressive muscle weakness that is often noted in early childhood.
- It is characterized by **proximal muscle wasting** and does not present with the specific dermatological findings of heliotrope rash or Gottron's papules.
*Polymyositis*
- Polymyositis also presents with **symmetric proximal muscle weakness**, similar to dermatomyositis, but it **lacks the characteristic skin manifestations** described in the patient.
- The absence of the heliotrope rash and Gottron's papules helps differentiate it from dermatomyositis.
*Hypothyroidism*
- Hypothyroidism can cause **muscle weakness**, myalgia, and cramps, but these symptoms are usually insidious and accompanied by other systemic symptoms like **fatigue**, **weight gain**, and **cold intolerance**.
- It does **not cause the specific skin rashes** (heliotrope rash, Gottron's papules) seen in this patient.
