2026 VERSION COMSAE Phase 2 Form
114i Exam Questions with Detailed
Rationales
Question 1
A 64-year-old man with a 45-pack-year smoking history
presents with progressive hoarseness, dysphagia, and a 7-kg
unintentional weight loss over 3 months. Examination reveals
a left supraclavicular lymph node. CT of the chest shows a 4-
cm hilar mass with mediastinal lymphadenopathy. Biopsy
demonstrates small cells with scant cytoplasm, finely granular
chromatin, and extensive necrosis. Which of the following is
the most likely diagnosis?
A. Squamous cell carcinoma
B. Adenocarcinoma
C. Small cell carcinoma
D. Large cell carcinoma
Rationale: Small cell carcinoma is strongly associated with
smoking and is characterised by small cells with scant
cytoplasm, finely granular "salt-and-pepper" chromatin,
nuclear moulding, and extensive necrosis. It commonly arises
centrally and frequently presents with mediastinal
involvement. Small cell carcinoma is highly aggressive and
often associated with paraneoplastic syndromes such as
SIADH and ectopic ACTH production. Squamous cell
,carcinoma can also be centrally located but typically
demonstrates keratinisation and intercellular bridges.
Adenocarcinoma is more commonly peripheral and forms
glandular structures.
Question 2
A 28-year-old woman presents with fatigue, weight loss, heat
intolerance, tremor, and palpitations. Examination shows a
diffusely enlarged thyroid gland and bilateral exophthalmos.
Laboratory studies reveal elevated free T4 and suppressed
TSH. Which of the following mechanisms best explains her
thyroid disease?
A. Autonomous thyroid follicular cell proliferation caused by a
TSH receptor mutation
B. Destruction of thyroid follicles by cytotoxic T cells
C. Autoantibodies that stimulate the TSH receptor
D. Autoantibodies that block thyroid peroxidase
Rationale: Graves disease results from IgG autoantibodies
that bind and stimulate the TSH receptor, causing increased
synthesis and release of thyroid hormones. The diffuse goitre
and ophthalmopathy are characteristic. Toxic multinodular
goitre results from autonomous nodules, while Hashimoto
thyroiditis involves autoimmune destruction of thyroid tissue
and typically causes hypothyroidism. Anti-thyroid peroxidase
antibodies are associated with autoimmune thyroid disease
but do not directly explain the hyperthyroid mechanism in
Graves disease.
,Question 3
A 71-year-old man with hypertension and chronic kidney
disease develops sudden right-sided weakness and expressive
aphasia. CT of the head demonstrates a haemorrhage
involving the left basal ganglia. Which of the following vessels
is most likely responsible?
A. Anterior cerebral artery
B. Middle cerebral artery
C. Lenticulostriate arteries
D. Posterior cerebral artery
Rationale: Hypertensive intracerebral haemorrhages
classically occur in the basal ganglia, thalamus, pons, and
cerebellum. The lenticulostriate arteries, small penetrating
branches of the middle cerebral artery, are particularly
vulnerable to chronic hypertension and Charcot-Bouchard
microaneurysm formation. A basal ganglia haemorrhage
therefore strongly suggests rupture of a lenticulostriate
vessel.
Question 4
A 59-year-old woman presents with severe chest pain
radiating to her left arm. ECG shows ST-segment elevations in
leads II, III, and aVF. She becomes hypotensive after receiving
sublingual nitroglycerin. Examination reveals elevated jugular
venous pressure and clear lung fields. Which of the following
is the most likely diagnosis?
, A. Left ventricular free-wall rupture
B. Acute mitral regurgitation
C. Right ventricular infarction
D. Ventricular septal rupture
Rationale: Inferior myocardial infarction with hypotension,
elevated JVP, and clear lungs is classic for right ventricular
infarction, usually caused by right coronary artery occlusion.
The right ventricle is preload-dependent, so venodilation from
nitroglycerin can significantly reduce preload and worsen
hypotension. Treatment typically involves cautious
intravenous fluid administration. Pulmonary oedema would
be more characteristic of left ventricular failure.
Question 5
A 34-year-old woman presents with recurrent episodes of
abdominal pain, psychiatric symptoms, and dark urine.
Laboratory testing shows elevated urinary porphobilinogen.
She recently began a medication for epilepsy. Which of the
following medications is most likely to precipitate her
condition?
A. Gabapentin
B. Levetiracetam
C. Phenytoin
D. Valproic acid
Rationale: Acute intermittent porphyria is caused by
decreased porphobilinogen deaminase activity and presents
with abdominal pain, neuropsychiatric symptoms, autonomic
114i Exam Questions with Detailed
Rationales
Question 1
A 64-year-old man with a 45-pack-year smoking history
presents with progressive hoarseness, dysphagia, and a 7-kg
unintentional weight loss over 3 months. Examination reveals
a left supraclavicular lymph node. CT of the chest shows a 4-
cm hilar mass with mediastinal lymphadenopathy. Biopsy
demonstrates small cells with scant cytoplasm, finely granular
chromatin, and extensive necrosis. Which of the following is
the most likely diagnosis?
A. Squamous cell carcinoma
B. Adenocarcinoma
C. Small cell carcinoma
D. Large cell carcinoma
Rationale: Small cell carcinoma is strongly associated with
smoking and is characterised by small cells with scant
cytoplasm, finely granular "salt-and-pepper" chromatin,
nuclear moulding, and extensive necrosis. It commonly arises
centrally and frequently presents with mediastinal
involvement. Small cell carcinoma is highly aggressive and
often associated with paraneoplastic syndromes such as
SIADH and ectopic ACTH production. Squamous cell
,carcinoma can also be centrally located but typically
demonstrates keratinisation and intercellular bridges.
Adenocarcinoma is more commonly peripheral and forms
glandular structures.
Question 2
A 28-year-old woman presents with fatigue, weight loss, heat
intolerance, tremor, and palpitations. Examination shows a
diffusely enlarged thyroid gland and bilateral exophthalmos.
Laboratory studies reveal elevated free T4 and suppressed
TSH. Which of the following mechanisms best explains her
thyroid disease?
A. Autonomous thyroid follicular cell proliferation caused by a
TSH receptor mutation
B. Destruction of thyroid follicles by cytotoxic T cells
C. Autoantibodies that stimulate the TSH receptor
D. Autoantibodies that block thyroid peroxidase
Rationale: Graves disease results from IgG autoantibodies
that bind and stimulate the TSH receptor, causing increased
synthesis and release of thyroid hormones. The diffuse goitre
and ophthalmopathy are characteristic. Toxic multinodular
goitre results from autonomous nodules, while Hashimoto
thyroiditis involves autoimmune destruction of thyroid tissue
and typically causes hypothyroidism. Anti-thyroid peroxidase
antibodies are associated with autoimmune thyroid disease
but do not directly explain the hyperthyroid mechanism in
Graves disease.
,Question 3
A 71-year-old man with hypertension and chronic kidney
disease develops sudden right-sided weakness and expressive
aphasia. CT of the head demonstrates a haemorrhage
involving the left basal ganglia. Which of the following vessels
is most likely responsible?
A. Anterior cerebral artery
B. Middle cerebral artery
C. Lenticulostriate arteries
D. Posterior cerebral artery
Rationale: Hypertensive intracerebral haemorrhages
classically occur in the basal ganglia, thalamus, pons, and
cerebellum. The lenticulostriate arteries, small penetrating
branches of the middle cerebral artery, are particularly
vulnerable to chronic hypertension and Charcot-Bouchard
microaneurysm formation. A basal ganglia haemorrhage
therefore strongly suggests rupture of a lenticulostriate
vessel.
Question 4
A 59-year-old woman presents with severe chest pain
radiating to her left arm. ECG shows ST-segment elevations in
leads II, III, and aVF. She becomes hypotensive after receiving
sublingual nitroglycerin. Examination reveals elevated jugular
venous pressure and clear lung fields. Which of the following
is the most likely diagnosis?
, A. Left ventricular free-wall rupture
B. Acute mitral regurgitation
C. Right ventricular infarction
D. Ventricular septal rupture
Rationale: Inferior myocardial infarction with hypotension,
elevated JVP, and clear lungs is classic for right ventricular
infarction, usually caused by right coronary artery occlusion.
The right ventricle is preload-dependent, so venodilation from
nitroglycerin can significantly reduce preload and worsen
hypotension. Treatment typically involves cautious
intravenous fluid administration. Pulmonary oedema would
be more characteristic of left ventricular failure.
Question 5
A 34-year-old woman presents with recurrent episodes of
abdominal pain, psychiatric symptoms, and dark urine.
Laboratory testing shows elevated urinary porphobilinogen.
She recently began a medication for epilepsy. Which of the
following medications is most likely to precipitate her
condition?
A. Gabapentin
B. Levetiracetam
C. Phenytoin
D. Valproic acid
Rationale: Acute intermittent porphyria is caused by
decreased porphobilinogen deaminase activity and presents
with abdominal pain, neuropsychiatric symptoms, autonomic
