System-based differential construction US Medical PG Practice Questions and MCQs
Practice US Medical PG questions for System-based differential construction. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
System-based differential construction US Medical PG Question 1: A 50-year-old woman presents with sudden onset right upper quadrant abdominal pain. She says her symptoms started 6 hours ago after she had dinner. She describes the pain as cramping, radiating to her shoulders. She had similar episodes in the past, but they were less severe and resolved with over-the-counter analgesics. Her medical history is significant for hypertension and coronary artery disease. Her current medications include warfarin, hydrochlorothiazide, and fibrates. Her temperature is 37.7°C (99.9°F), blood pressure is 110/80 mm Hg, pulse is 80/min, and respirations are 15/min. Abdominal exam reveals severe right upper quadrant tenderness, and she catches her breath when palpated deeply just below the right costal margin. Surgical consult determines her to be surgically unfit for any intervention due to her high risk of bleeding. After treating her pain with appropriate analgesics, which of the following is the next best step in the management of this patient?
- A. Antispasmodic therapy (hyoscine butylbromide) (Correct Answer)
- B. Re-evaluate after few hours and perform laparoscopic cholecystectomy
- C. Discontinue fibrates
- D. Initiate stronger analgesic medications such as morphine
- E. No need for further treatment
System-based differential construction Explanation: ***Antispasmodic therapy (hyoscine butylbromide)***
- The patient presents with symptoms highly suggestive of **biliary colic**, including right upper quadrant pain radiating to the shoulder, exacerbated by a fatty meal, and a positive Murphy's sign (catching her breath on deep palpation). Given she is surgically unfit due to anticoagulation, **medical management** for pain and spasm relief is the priority.
- Hyoscine butylbromide is an **anticholinergic agent** that helps relax smooth muscles of the gastrointestinal tract, including the biliary tree, thereby reducing the painful spasms associated with biliary colic.
*Re-evaluate after few hours and perform laparoscopic cholecystectomy*
- While **laparoscopic cholecystectomy** is the definitive treatment for symptomatic cholelithiasis, the patient's current use of **warfarin** makes her surgically unfit due to a high bleeding risk.
- Proceeding with surgery, even after re-evaluation, without addressing the anticoagulation and bleeding risk would be **unsafe** and could lead to severe hemorrhagic complications.
*Discontinue fibrates*
- Fibrates, like fenofibrate or gemfibrozil, can **increase the risk of gallstone formation** (cholelithiasis) by altering bile composition. However, discontinuing them acutely would not immediately resolve the current episode of biliary colic.
- While it may be a consideration for **long-term management** to prevent future episodes, it is not the immediate best step for managing the acute symptomatic presentation.
*Initiate stronger analgesic medications such as morphine*
- Although the patient is in severe pain, **morphine** and other opioids can paradoxically **increase spasm of the sphincter of Oddi**, potentially worsening biliary colic rather than relieving it.
- While effective for general pain relief, opioids like morphine are **generally avoided** in the initial management of suspected biliary colic due to this side effect.
*No need for further treatment*
- The patient is experiencing an acute, severe episode of **biliary colic** requiring urgent symptomatic relief. Her pain is significant, describing it as cramping, and she has a positive Murphy's sign.
- Dismissing the need for further treatment would be **inappropriate** and would leave the patient suffering, potentially leading to complications if the obstruction is prolonged.
System-based differential construction US Medical PG Question 2: A 25-year-old man comes to the physician for severe back pain. He describes the pain as shooting and stabbing. On a 10-point scale, he rates the pain as a 9 to 10. The pain started after he lifted a heavy box at work; he works at a supermarket and recently switched from being a cashier to a storekeeper. The patient appears to be in severe distress. Vital signs are within normal limits. On physical examination, the spine is nontender without paravertebral muscle spasms. Range of motion is normal. A straight-leg raise test is negative. After the physical examination has been completed, the patient asks for a letter to his employer attesting to his inability to work as a storekeeper. Which of the following is the most appropriate response?
- A. “Yes. Since work may worsen your condition, I would prefer that you stay home a few days. I will write a letter to your employer to explain the situation.”
- B. You say you are in severe pain. However, the physical examination findings do not suggest a physical problem that can be addressed with medications or surgery. I'd like to meet on a regular basis to see how you're doing.
- C. I understand that you are uncomfortable, but the findings do not match the severity of your symptoms. Let's talk about the recent changes at your job. (Correct Answer)
- D. The physical exam findings do not match your symptoms, which suggests a psychological problem. I would be happy to refer you to a mental health professional.
- E. The physical exam findings suggest a psychological rather than a physical problem. But there is a good chance that we can address it with cognitive-behavioral therapy.
System-based differential construction Explanation: ***"I understand that you are uncomfortable, but the findings do not match the severity of your symptoms. Let's talk about the recent changes at your job."***
- This response acknowledges the patient's reported discomfort while gently highlighting the **discrepancy between symptoms and objective findings**, which is crucial in cases of suspected **somatoform or functional pain**.
- It also opens communication about potential **psychosocial stressors** related to his job change, which could be contributing to his symptoms, without dismissing his pain or making a premature diagnosis.
*"You say you are in severe pain. However, the physical examination findings do not suggest a physical problem that can be addressed with medications or surgery. I'd like to meet on a regular basis to see how you're doing."*
- While this option correctly identifies the lack of physical findings, it can be perceived as dismissive of the patient's pain, potentially damaging the **physician-patient relationship**.
- Suggesting regular meetings without a clear plan for addressing his immediate concerns or exploring underlying issues might not be the most effective initial approach.
*“Yes. Since work may worsen your condition, I would prefer that you stay home a few days. I will write a letter to your employer to explain the situation.”*
- This response would **validate the patient's claim of severe pain** without objective evidence, potentially reinforcing illness behavior and avoiding addressing the underlying issue.
- Providing a doctor's note for inability to work without a clear diagnostic basis or understanding of the pain's origin is **medically inappropriate** and could set a precedent for future such requests.
*"The physical exam findings do not match your symptoms, which suggests a psychological problem. I would be happy to refer you to a mental health professional."*
- Directly labeling the problem as "psychological" can be **stigmatizing and alienating** to the patient, leading to distrust and resistance to care.
- While a psychological component might be present, immediately referring to mental health without further exploration of the patient's situation or current stressors is premature and lacks empathy.
*"The physical exam findings suggest a psychological rather than a physical problem. But there is a good chance that we can address it with cognitive-behavioral therapy."*
- Similar to the previous option, explicitly stating a "psychological problem" can be **stigmatizing**.
- Jumping directly to recommending **cognitive-behavioral therapy (CBT)** without a comprehensive discussion and patient buy-in is premature and may lead to non-compliance.
System-based differential construction US Medical PG Question 3: A 52-year-old man comes to the physician because of a 3-week history of a cough and hoarseness. He reports that the cough is worse when he lies down after lunch. His temperature is 37.5°C (99.5°F); the remainder of his vital signs are within normal limits. Because the physician has recently been seeing several patients with the common cold, the diagnosis of a viral upper respiratory tract infection readily comes to mind. The physician fails to consider the diagnosis of gastroesophageal reflux disease, which the patient is later found to have. Which of the following most accurately describes the cognitive bias that the physician had?
- A. Framing
- B. Anchoring
- C. Visceral
- D. Confirmation
- E. Availability (Correct Answer)
System-based differential construction Explanation: ***Availability***
- The physician recently seeing several patients with the common cold led to this diagnosis readily coming to mind, demonstrating how easily recalled examples can disproportionately influence diagnosis.
- This bias occurs when easily recalled instances or information (like recent cases of common cold) are used to estimate the likelihood or frequency of an event, even if other more relevant data exist.
*Framing*
- This bias occurs when the way information is presented (e.g., as a gain or a loss) influences a decision, rather than the intrinsic characteristics of the options themselves.
- The scenario does not involve the presentation of information in different ways to sway the physician's judgment.
*Anchoring*
- This bias involves relying too heavily on an initial piece of information (the "anchor") when making subsequent judgments, often leading to insufficient adjustment away from that anchor.
- While the physician initially considered a viral URI, the setup is more about the ease of recall influencing the decision rather than being stuck on an initial data point.
*Visceral*
- This is not a commonly recognized cognitive bias in the context of medical decision-making; "visceral" largely refers to emotional or intuitive feelings rather than a structured cognitive bias.
- Cognitive biases describe systematic patterns of deviation from norm or rationality in judgment, not merely emotional responses.
*Confirmation*
- This bias involves seeking, interpreting, favoring, and recalling information in a way that confirms one's pre-existing beliefs or hypotheses.
- The physician did not actively seek information to confirm the common cold diagnosis; rather, the diagnosis came to mind due to recent encounters, which aligns with availability bias.
System-based differential construction US Medical PG Question 4: A 72-year-old woman is brought to the emergency department with dyspnea for 2 days. She is on regular hemodialysis at 3 sessions a week but missed her last session due to an unexpected trip. She has a history of congestive heart failure. After urgent hemodialysis, the patient’s dyspnea does not improve as expected. The cardiologist is consulted. After evaluation of the patient, he notes in the patient’s electronic record: “the patient does not have a chronic heart condition and a cardiac cause of dyspnea is unlikely.” The following morning, the nurse finds the cardiologist’s notes about the patient not having congestive heart failure odd. The patient had a clear history of congestive heart failure with an ejection fraction of 35%. After further investigation, the nurse realizes that the cardiologist evaluated the patient’s roommate. She is an elderly woman with a similar first name. She is also on chronic hemodialysis. To prevent similar future errors, the most appropriate strategy is to use which of the following?
- A. Two patient identifiers at every nurse-patient encounter
- B. A patient’s medical identification number at every encounter by any healthcare provider
- C. Two patient identifiers at every patient encounter by any healthcare provider (Correct Answer)
- D. Two patient identifiers at every physician-patient encounter
- E. A patient’s medical identification number at every physician-patient encounter
System-based differential construction Explanation: ***Two patient identifiers at every patient encounter by any healthcare provider***
- This strategy ensures that **all healthcare providers**, not just nurses or physicians, verify the patient's identity using at least **two distinct identifiers** before any interaction, greatly reducing the risk of mix-ups.
- This comprehensive approach prevents errors like the one described, where a cardiologist evaluated the wrong patient due to similar names and circumstances, ensuring **patient safety** and appropriate care delivery.
*Two patient identifiers at every nurse-patient encounter*
- While important, limiting identification to nurse-patient encounters would **miss opportunities for error by other healthcare providers**, such as physicians, technicians, or pharmacists.
- The scenario explicitly states the error was made by a **cardiologist**, indicating that relying solely on nurses for identification is insufficient.
*A patient’s medical identification number at every encounter by any healthcare provider*
- Although the **medical identification number** is a valid identifier, relying on a *single* identifier still carries a risk, especially if typed or read incorrectly.
- **Two distinct identifiers** (e.g., name and date of birth, or name and medical record number) are the **gold standard** to minimize errors.
*Two patient identifiers at every physician-patient encounter*
- This option, while improving physician encounters, **fails to cover interactions with other crucial healthcare team members** (e.g., nurses, phlebotomists, imaging technicians) where patient misidentification can still occur.
- A comprehensive patient safety strategy must extend beyond physician interactions to **all points of care**.
*A patient’s medical identification number at every physician-patient encounter*
- This option combines the weaknesses of using only a **single identifier** and limiting the scope to **only physician encounters**, leaving multiple vulnerabilities for patient misidentification throughout the healthcare process.
- The **Joint Commission's National Patient Safety Goals** explicitly recommend using at least **two patient identifiers**.
System-based differential construction US Medical PG Question 5: A 67-year-old man presents to the emergency department with confusion. The patient is generally healthy, but his wife noticed him becoming progressively more confused as the day went on. The patient is not currently taking any medications and has no recent falls or trauma. His temperature is 102°F (38.9°C), blood pressure is 126/64 mmHg, pulse is 120/min, respirations are 17/min, and oxygen saturation is 98% on room air. Physical exam is notable for a confused man who cannot participate in a neurological exam secondary to his confusion. No symptoms are elicited with flexion of the neck and jolt accentuation of headache is negative. Initial laboratory values are unremarkable and the patient's chest radiograph and urinalysis are within normal limits. An initial CT scan of the head is unremarkable. Which of the following is the best next step in management?
- A. CT angiogram of the head and neck
- B. Vancomycin, ceftriaxone, ampicillin, and dexamethasone
- C. Acyclovir (Correct Answer)
- D. PCR of the cerebrospinal fluid
- E. MRI of the head
System-based differential construction Explanation: ***Acyclovir***
- This patient presents with **acute confusion and fever** without an obvious infectious source, negative meningeal signs, and normal initial imaging, highly suggestive of **herpes simplex encephalitis (HSE)**.
- HSE is a **medical emergency** with high mortality (70-80%) if untreated, but mortality drops to 20-30% with early acyclovir therapy.
- **Empiric acyclovir must be started immediately** upon clinical suspicion of HSE, **without waiting for diagnostic confirmation**.
- Standard management includes obtaining CSF for PCR **concurrently** with starting acyclovir, but treatment should never be delayed for diagnostic testing.
- The best next step in **management** is initiating acyclovir; CSF PCR is obtained for confirmation but does not delay treatment.
*PCR of the cerebrospinal fluid*
- **CSF PCR for HSV** is the gold standard **diagnostic test** for HSE with high sensitivity (96%) and specificity (99%).
- While lumbar puncture should be performed to obtain CSF for PCR, this is a **diagnostic step** that should be done **concurrently** with starting acyclovir, not instead of it.
- The question asks for best next step in **management**, not diagnosis—acyclovir therapy takes precedence.
- Delaying acyclovir while awaiting diagnostic confirmation significantly increases morbidity and mortality.
*Vancomycin, ceftriaxone, ampicillin, and dexamethasone*
- This broad-spectrum antibiotic regimen is empiric therapy for **bacterial meningitis** and should be considered in patients with fever and altered mental status.
- However, the **absence of meningeal signs** (negative nuchal rigidity, negative jolt accentuation) makes bacterial meningitis less likely.
- In practice, when HSE is suspected but bacterial meningitis cannot be excluded, both antimicrobial regimens may be initiated empirically, but the primary concern here is HSE given the clinical presentation.
*MRI of the head*
- **MRI with FLAIR sequences** is highly sensitive for HSE and typically shows **temporal lobe involvement** (especially medial temporal lobes).
- However, MRI findings may be **normal early in the disease course** (first 48-72 hours).
- MRI is useful for supporting the diagnosis but should **not delay empiric acyclovir therapy**.
- Obtaining MRI before treatment would be inappropriate given the time-sensitive nature of HSE.
*CT angiogram of the head and neck*
- CT angiography evaluates vascular structures and is indicated for suspected **stroke, aneurysm, or vascular dissection**.
- This patient lacks focal neurological deficits, signs of acute stroke, or vascular risk factors that would prioritize vascular imaging.
- The presentation with fever and diffuse encephalopathy points toward an infectious/inflammatory process rather than a vascular etiology.
System-based differential construction US Medical PG Question 6: A 28-year-old male presents to his primary care physician with complaints of intermittent abdominal pain and alternating bouts of constipation and diarrhea. His medical chart is not significant for any past medical problems or prior surgeries. He is not prescribed any current medications. Which of the following questions would be the most useful next question in eliciting further history from this patient?
- A. "Does the diarrhea typically precede the constipation, or vice-versa?"
- B. "Is the diarrhea foul-smelling?"
- C. "Please rate your abdominal pain on a scale of 1-10, with 10 being the worst pain of your life"
- D. "Are the symptoms worse in the morning or at night?"
- E. "Can you tell me more about the symptoms you have been experiencing?" (Correct Answer)
System-based differential construction Explanation: ***Can you tell me more about the symptoms you have been experiencing?***
- This **open-ended question** encourages the patient to provide a **comprehensive narrative** of their symptoms, including details about onset, frequency, duration, alleviating/aggravating factors, and associated symptoms, which is crucial for diagnosis.
- In a patient presenting with vague, intermittent symptoms like alternating constipation and diarrhea, allowing them to elaborate freely can reveal important clues that might not be captured by more targeted questions.
*Does the diarrhea typically precede the constipation, or vice-versa?*
- While knowing the sequence of symptoms can be helpful in understanding the **pattern of bowel dysfunction**, it is a very specific question that might overlook other important aspects of the patient's experience.
- It prematurely narrows the focus without first obtaining a broad understanding of the patient's overall symptomatic picture.
*Is the diarrhea foul-smelling?*
- Foul-smelling diarrhea can indicate **malabsorption** or **bacterial overgrowth**, which are important to consider in some gastrointestinal conditions.
- However, this is a **specific symptom inquiry** that should follow a more general exploration of the patient's symptoms, as it may not be relevant if other crucial details are missed.
*Please rate your abdominal pain on a scale of 1-10, with 10 being the worst pain of your life*
- Quantifying pain intensity is useful for assessing the **severity of discomfort** and monitoring changes over time.
- However, for a patient with intermittent rather than acute, severe pain, understanding the **character, location, and triggers** of the pain is often more diagnostically valuable than just a numerical rating initially.
*Are the symptoms worse in the morning or at night?*
- Diurnal variation can be relevant in certain conditions, such as inflammatory bowel diseases where nocturnal symptoms might be more concerning, or functional disorders whose symptoms might be stress-related.
- This is another **specific question** that should come after gathering a more complete initial picture of the patient's symptoms to ensure no key information is overlooked.
System-based differential construction US Medical PG Question 7: A 65-year-old man is admitted to the hospital because of a 1-month history of fatigue, intermittent fever, and weakness. Results from a peripheral blood smear taken during his evaluation are indicative of possible acute myeloid leukemia. Bone marrow aspiration and subsequent cytogenetic studies confirm the diagnosis. The physician sets aside an appointed time-slot and arranges a meeting in a quiet office to inform him about the diagnosis and discuss his options. He has been encouraged to bring someone along to the appointment if he wanted. He comes to your office at the appointed time with his daughter. He appears relaxed, with a full range of affect. Which of the following is the most appropriate opening statement in this situation?
- A. Your lab reports show that you have an acute myeloid leukemia
- B. What is your understanding of the reasons we did bone marrow aspiration and cytogenetic studies? (Correct Answer)
- C. You must be curious and maybe even anxious about the results of your tests.
- D. I may need to refer you to a blood cancer specialist because of your diagnosis. You may need chemotherapy or radiotherapy, which we are not equipped for.
- E. Would you like to know all the details of your diagnosis, or would you prefer I just explain to you what our options are?
System-based differential construction Explanation: ***"What is your understanding of the reasons we did bone marrow aspiration and cytogenetic studies?"***
- This **open-ended question** allows the patient to express their current knowledge and perceptions, which helps the physician tailor the discussion.
- It establishes a **patient-centered approach**, respecting the patient's existing understanding and preparing them for further information.
*"You must be curious and maybe even anxious about the results of your tests."*
- While empathic, this statement makes an **assumption about the patient's feelings** rather than inviting them to share their own.
- It is often better to ask directly or use more open-ended questions that allow the patient to express their true emotions, especially given their **relaxed demeanor**.
*"I may need to refer you to a blood cancer specialist because of your diagnosis. You may need chemotherapy or radiotherapy, which we are not equipped for.”"*
- This statement immediately introduces **overwhelming and potentially alarming information** (referral, chemotherapy, radiotherapy) without first establishing the diagnosis or assessing the patient's readiness to receive it.
- It prematurely jumps to treatment and logistics, potentially causing **unnecessary distress** before the patient has processed the core diagnosis.
*"Would you like to know all the details of your diagnosis, or would you prefer I just explain to you what our options are?""*
- While it attempts to assess the patient's preference for information, this question is a **closed-ended "either/or" choice** that might limit the patient's ability to express nuanced needs.
- It also prematurely introduces the idea of "options" without first explaining the diagnosis in an understandable context.
*"Your lab reports show that you have an acute myeloid leukemia"*
- This is a **direct and blunt delivery of a serious diagnosis** without any preparatory context or assessment of the patient's existing knowledge or emotional state.
- Delivering such news abruptly can be shocking and overwhelming, potentially **hindering effective communication** and rapport building.
System-based differential construction US Medical PG Question 8: 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
System-based differential construction 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.
System-based differential construction US Medical PG Question 9: 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
System-based differential construction 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.
System-based differential construction US Medical PG Question 10: A 22-year-old man is evaluated for abdominal discomfort he has had for the past 6 days and fever for the past 2 weeks. He also notes that his right upper abdomen is bothering him. He states that he does not drink alcohol or use illicit drugs. His medical history is insignificant and family history is negative for any liver disease. On physical examination, his temperature is 38.0°C (100.4°F), blood pressure is 120/80 mm Hg, pulse rate is 102/min, and respiratory rate is 22/min. He is alert and oriented. Scleral icterus and hepatomegaly are noted. Laboratory results are as follows:
Anti-hepatitis A IgM positive
Anti-hepatitis A IgG negative
Hepatitis B surface Ag negative
Hepatitis B surface AB negative
Alanine aminotransferase 1544 U/L
Aspartate aminotransferase 1200 U/L
Which of the following transcription factors is required for the B cells to differentiate into plasma cells in this patient?
- A. Metastasis-associated 1 family, member 3 (MTA-3)
- B. Microphthalmia-associated transcription factor (MITF)
- C. Paired box protein 5 (PAX5)
- D. B cell lymphoma 6 (BCL6)
- E. B lymphocyte induced maturation protein 1 (BLIMP1) (Correct Answer)
System-based differential construction Explanation: ***B lymphocyte induced maturation protein 1 (BLIMP1)***
- The positive **anti-hepatitis A IgM** and negative **IgG** indicates an **acute hepatitis A infection**, triggering a primary immune response where **B cells differentiate into plasma cells** to produce antibodies.
- **BLIMP1** (B lymphocyte-induced maturation protein 1) is a master regulator that promotes plasma cell differentiation by **repressing key B cell transcription factors** and activating plasma cell-specific genes.
*Metastasis-associated 1 family, member 3 (MTA-3)*
- **MTA-3** is a component of the **NuRD corepressor complex** and is involved in various cellular processes including transcriptional repression and chromatin remodeling.
- While it plays a role in B cell development and germinal center reactions, it is **not directly required for the terminal differentiation of B cells into plasma cells**; instead, it is involved in maintaining germinal center B cell identity.
*Microphthalmia-associated transcription factor (MITF)*
- **MITF** is a transcription factor primarily known for its role in the **development and function of melanocytes**, mast cells, and osteoclasts.
- It is **not involved in the differentiation of B cells into plasma cells** in the context of an immune response.
*Paired box protein 5 (PAX5)*
- **PAX5** is a crucial transcription factor for **B cell development** and maintaining B cell identity, acting as a repressor of non-B cell lineages.
- Its expression must be **downregulated for B cells to differentiate into plasma cells**, as it inhibits the plasma cell differentiation program.
*B cell lymphoma 6 (BCL6)*
- **BCL6** is a transcriptional repressor critical for the **formation and maintenance of germinal centers**, where B cells undergo proliferation, somatic hypermutation, and class-switch recombination.
- It **inhibits plasma cell differentiation**, and its downregulation is necessary for B cells to commit to becoming plasma cells.
More System-based differential construction US Medical PG questions available in the OnCourse app. Practice MCQs, flashcards, and get detailed explanations.
