NBME CBSE REAL EXAM 110
QUESTIONS AND ANSWERS LATEST
2026 COMPLETE EXAM /MEDICAL
EXAMINATION/
1. A 55-year-old man with a 40-pack-year smoking history
presents with hemoptysis and weight loss. Chest CT shows a 3
cm right hilar mass. Bronchoscopy biopsy reveals small cells
with scant cytoplasm, salt-and-pepper chromatin, and high
mitotic rate. Which paraneoplastic syndrome is most likely?
Answer: SIADH (syndrome of inappropriate antidiuretic hormone
secretion)
Rationale: Small cell lung cancer (SCLC) is strongly associated
with paraneoplastic SIADH due to ectopic ADH production. Other
common paraneoplastic syndromes in SCLC include Lambert-
Eaton myasthenic syndrome and ectopic ACTH secretion. The
histology (small cells, salt-and-pepper chromatin) is classic for
SCLC.
2. A 28-year-old woman presents with episodic palpitations,
sweating, and headache. Her blood pressure is 210/110
mmHg during an episode. CT reveals a 4 cm left adrenal mass.
What is the most appropriate confirmatory test?
,Answer: Plasma-free metanephrines
Rationale: The presentation suggests pheochromocytoma.
Plasma-free metanephrines have the highest sensitivity for
diagnosis. MRI/CT localize the tumor but do not confirm
functionality. Urinary VMA is less sensitive.
3. A 45-year-old man with cirrhosis presents with confusion,
asterixis, and elevated ammonia. Which medication directly
reduces ammonia production by gut bacteria?
Answer: Rifaximin
Rationale: Rifaximin is a non-absorbable antibiotic that reduces
gut bacteria, decreasing ammonia production. Lactulose works by
acidifying the colon to trap NH4+ (non-absorbable) and
promoting bowel movements. Neomycin is another option but
has more systemic toxicity.
4. A 70-year-old woman on long-term alendronate for
osteoporosis develops severe thigh pain. X-ray shows a
transverse lucent line in the lateral femoral cortex. What is
the diagnosis?
Answer: Atypical femoral fracture
Rationale: Bisphosphonates (alendronate) suppress bone
turnover, leading to atypical femoral fractures. They are often
preceded by prodromal thigh pain and have characteristic
,radiographic findings (transverse fracture line, beaking of lateral
cortex).
5. A 3-year-old boy presents with recurrent sinopulmonary
infections and chronic diarrhea. Serum immunoglobulins
show absent IgA, low IgG, and elevated IgM. Flow cytometry
shows normal B-cell and T-cell counts. What is the most likely
diagnosis?
Answer: Hyper-IgM syndrome
Rationale: This pattern (low IgG/IgA, high IgM, recurrent
infections) is classic for hyper-IgM syndrome, most often due to
CD40 ligand deficiency (X-linked). It causes defective class-
switching. X-linked agammaglobulinemia would have very low all
immunoglobulins and no B cells.
6. A 60-year-old man with hypertension is started on
lisinopril. Two weeks later, he presents with a nonproductive
cough. What is the mechanism of this adverse effect?
Answer: Increased bradykinin levels
Rationale: ACE inhibitors (lisinopril) block the degradation of
bradykinin, leading to its accumulation and causing a dry cough.
Angiotensin receptor blockers (ARBs) do not affect bradykinin and
have lower cough risk.
, 7. A 25-year-old woman has a painless thyroid nodule. Fine-
needle aspiration shows cells with intranuclear cytoplasmic
pseudoinclusions and orphan Annie nuclei. What is the most
likely diagnosis?
Answer: Papillary thyroid carcinoma
Rationale: Orphan Annie eyes (nuclear clearing) and intranuclear
pseudoinclusions are pathognomonic for papillary thyroid
carcinoma. Psammoma bodies are also characteristic. Medullary
carcinoma shows amyloid and calcitonin positivity.
8. A 65-year-old man with a history of MI is on aspirin and
clopidogrel. He presents with melena. Upper endoscopy
reveals a clean-based duodenal ulcer. What is the most likely
mechanism of the ulcer?
Answer: Reduced mucosal prostaglandin synthesis
Rationale: Aspirin irreversibly inhibits COX-1, reducing
prostaglandin E2 and I2, which impairs gastric mucosal defense.
Clopidogrel (P2Y12 inhibitor) does not directly cause ulcers but
can exacerbate bleeding from pre-existing lesions.
9. A 30-year-old man presents with acute-onset unilateral
vision loss that resolves spontaneously after 30 minutes.
QUESTIONS AND ANSWERS LATEST
2026 COMPLETE EXAM /MEDICAL
EXAMINATION/
1. A 55-year-old man with a 40-pack-year smoking history
presents with hemoptysis and weight loss. Chest CT shows a 3
cm right hilar mass. Bronchoscopy biopsy reveals small cells
with scant cytoplasm, salt-and-pepper chromatin, and high
mitotic rate. Which paraneoplastic syndrome is most likely?
Answer: SIADH (syndrome of inappropriate antidiuretic hormone
secretion)
Rationale: Small cell lung cancer (SCLC) is strongly associated
with paraneoplastic SIADH due to ectopic ADH production. Other
common paraneoplastic syndromes in SCLC include Lambert-
Eaton myasthenic syndrome and ectopic ACTH secretion. The
histology (small cells, salt-and-pepper chromatin) is classic for
SCLC.
2. A 28-year-old woman presents with episodic palpitations,
sweating, and headache. Her blood pressure is 210/110
mmHg during an episode. CT reveals a 4 cm left adrenal mass.
What is the most appropriate confirmatory test?
,Answer: Plasma-free metanephrines
Rationale: The presentation suggests pheochromocytoma.
Plasma-free metanephrines have the highest sensitivity for
diagnosis. MRI/CT localize the tumor but do not confirm
functionality. Urinary VMA is less sensitive.
3. A 45-year-old man with cirrhosis presents with confusion,
asterixis, and elevated ammonia. Which medication directly
reduces ammonia production by gut bacteria?
Answer: Rifaximin
Rationale: Rifaximin is a non-absorbable antibiotic that reduces
gut bacteria, decreasing ammonia production. Lactulose works by
acidifying the colon to trap NH4+ (non-absorbable) and
promoting bowel movements. Neomycin is another option but
has more systemic toxicity.
4. A 70-year-old woman on long-term alendronate for
osteoporosis develops severe thigh pain. X-ray shows a
transverse lucent line in the lateral femoral cortex. What is
the diagnosis?
Answer: Atypical femoral fracture
Rationale: Bisphosphonates (alendronate) suppress bone
turnover, leading to atypical femoral fractures. They are often
preceded by prodromal thigh pain and have characteristic
,radiographic findings (transverse fracture line, beaking of lateral
cortex).
5. A 3-year-old boy presents with recurrent sinopulmonary
infections and chronic diarrhea. Serum immunoglobulins
show absent IgA, low IgG, and elevated IgM. Flow cytometry
shows normal B-cell and T-cell counts. What is the most likely
diagnosis?
Answer: Hyper-IgM syndrome
Rationale: This pattern (low IgG/IgA, high IgM, recurrent
infections) is classic for hyper-IgM syndrome, most often due to
CD40 ligand deficiency (X-linked). It causes defective class-
switching. X-linked agammaglobulinemia would have very low all
immunoglobulins and no B cells.
6. A 60-year-old man with hypertension is started on
lisinopril. Two weeks later, he presents with a nonproductive
cough. What is the mechanism of this adverse effect?
Answer: Increased bradykinin levels
Rationale: ACE inhibitors (lisinopril) block the degradation of
bradykinin, leading to its accumulation and causing a dry cough.
Angiotensin receptor blockers (ARBs) do not affect bradykinin and
have lower cough risk.
, 7. A 25-year-old woman has a painless thyroid nodule. Fine-
needle aspiration shows cells with intranuclear cytoplasmic
pseudoinclusions and orphan Annie nuclei. What is the most
likely diagnosis?
Answer: Papillary thyroid carcinoma
Rationale: Orphan Annie eyes (nuclear clearing) and intranuclear
pseudoinclusions are pathognomonic for papillary thyroid
carcinoma. Psammoma bodies are also characteristic. Medullary
carcinoma shows amyloid and calcitonin positivity.
8. A 65-year-old man with a history of MI is on aspirin and
clopidogrel. He presents with melena. Upper endoscopy
reveals a clean-based duodenal ulcer. What is the most likely
mechanism of the ulcer?
Answer: Reduced mucosal prostaglandin synthesis
Rationale: Aspirin irreversibly inhibits COX-1, reducing
prostaglandin E2 and I2, which impairs gastric mucosal defense.
Clopidogrel (P2Y12 inhibitor) does not directly cause ulcers but
can exacerbate bleeding from pre-existing lesions.
9. A 30-year-old man presents with acute-onset unilateral
vision loss that resolves spontaneously after 30 minutes.
