COMSAE PHASE 1 FORM 115 PRACTICE
EXAM WITH ACTUAL QUESTIONS AND
VERIFIED ANSWERS, PLUS EXPLAINED
RATIONALES/EXPERT VERIFIED FOR
GUARANTEED 100% PASS 2026/LATEST
UPDATE/INSTANT DOWNLOAD PDF
Question 1
A 24-year-old woman presents with fatigue, weight loss, heat
intolerance, palpitations, and increased bowel frequency. She has a
diffusely enlarged, nontender thyroid and bilateral exophthalmos.
Laboratory studies show an undetectable TSH and markedly elevated
free T4. Thyroid-stimulating immunoglobulins are positive. She is
started on methimazole.
Which mechanism best explains the underlying thyroid disorder?
A. Destruction of thyroid follicles by cytotoxic T lymphocytes
B. Antibodies that stimulate the TSH receptor
C. Autonomous activation of Gs proteins within thyroid follicular cells
D. Antibodies directed against thyroglobulin causing thyroid destruction
E. Excess hypothalamic production of thyrotropin-releasing hormone
Answer: B. Antibodies that stimulate the TSH receptor
Rationale: Graves disease is caused by thyroid-stimulating
immunoglobulins, which are IgG autoantibodies that bind and activate
the TSH receptor on thyroid follicular cells. This increases thyroid
hormone synthesis and gland growth. The suppressed TSH is a
consequence of negative feedback. Diffuse goiter and ophthalmopathy
strongly support Graves disease. Cytotoxic destruction is more
characteristic of Hashimoto thyroiditis.
1
,Question 2
A 67-year-old man with a 50-pack-year smoking history develops
progressive painless hematuria. Urinalysis confirms numerous red blood
cells without significant proteinuria or casts. CT imaging demonstrates a
mass arising from the lateral wall of the urinary bladder. Cystoscopy
reveals a papillary lesion projecting into the bladder lumen.
Which histologic finding is most likely associated with this malignancy?
A. Keratin pearls
B. Gland formation containing mucin
C. Urothelial cells with nuclear atypia and papillary architecture
D. Sheets of small round blue cells with Homer Wright rosettes
E. Spindle cells arranged in fascicles with cigar-shaped nuclei
Answer: C. Urothelial cells with nuclear atypia and papillary
architecture
Rationale: The most common bladder malignancy is urothelial
carcinoma, which classically presents with painless gross hematuria.
Smoking is a major risk factor because carcinogens are excreted into
the urine and expose the urothelium. Papillary tumors project into the
bladder lumen and demonstrate atypical urothelial cells. Keratin
pearls suggest squamous carcinoma, while gland formation suggests
adenocarcinoma.
Question 3
A 58-year-old woman presents with severe substernal chest pressure
radiating to her left arm. ECG demonstrates ST-segment elevations in
leads II, III, and aVF. She undergoes urgent coronary angiography,
which reveals complete occlusion of the right coronary artery.
Which region of the myocardium is most likely ischemic?
2
,A. Anterior wall and interventricular septum
B. Lateral wall
C. Inferior wall
D. Posterior wall exclusively
E. High anterolateral wall
Answer: C. Inferior wall
Rationale: The right coronary artery most commonly supplies the
inferior myocardium through the posterior descending artery in a
right-dominant circulation. ST elevation in leads II, III, and aVF
indicates an inferior myocardial infarction. RCA occlusion can also
compromise the AV node and cause bradyarrhythmias because the AV
nodal artery commonly arises from the RCA.
Question 4
A 9-year-old boy develops periorbital edema and cola-colored urine 2
weeks after recovering from impetigo. Blood pressure is 150/95 mm Hg.
Urinalysis reveals dysmorphic RBCs and RBC casts. Serum complement
C3 is decreased.
Which renal finding is most likely present?
A. Linear IgG deposition along the glomerular basement membrane
B. Subepithelial immune complex humps
C. Mesangial IgA deposition
D. Diffuse podocyte foot-process effacement without immune deposits
E. Crescent formation caused by anti-neutrophil cytoplasmic antibodies
Answer: B. Subepithelial immune complex humps
Rationale: Poststreptococcal glomerulonephritis is an immune
complex–mediated nephritic syndrome occurring after infection with
nephritogenic strains of Streptococcus pyogenes. Immune complexes
produce granular deposition, including characteristic subepithelial
3
, humps on electron microscopy. Low C3 typically returns to normal
within several weeks. IgA nephropathy generally occurs within days of
an upper respiratory or gastrointestinal infection rather than after a
prolonged latent period.
Question 5
A 35-year-old woman has recurrent episodes of severe abdominal pain,
peripheral neuropathy, anxiety, and dark urine. She has previously
undergone several unnecessary abdominal surgeries because of
unexplained pain. During an episode, laboratory testing demonstrates
markedly increased urinary porphobilinogen.
Which enzyme deficiency is most likely responsible?
A. Ferrochelatase
B. ALA dehydratase
C. Porphobilinogen deaminase
D. Uroporphyrinogen decarboxylase
E. Coproporphyrinogen oxidase
Answer: C. Porphobilinogen deaminase
Rationale: Acute intermittent porphyria results from deficiency of
porphobilinogen deaminase, also called hydroxymethylbilane
synthase. It causes episodic neurovisceral symptoms including
abdominal pain, peripheral neuropathy, psychiatric symptoms, and
autonomic dysfunction. Urine may become dark after standing.
Attacks can be precipitated by drugs, fasting, alcohol, and hormonal
changes. Photosensitivity is absent.
Question 6
4
EXAM WITH ACTUAL QUESTIONS AND
VERIFIED ANSWERS, PLUS EXPLAINED
RATIONALES/EXPERT VERIFIED FOR
GUARANTEED 100% PASS 2026/LATEST
UPDATE/INSTANT DOWNLOAD PDF
Question 1
A 24-year-old woman presents with fatigue, weight loss, heat
intolerance, palpitations, and increased bowel frequency. She has a
diffusely enlarged, nontender thyroid and bilateral exophthalmos.
Laboratory studies show an undetectable TSH and markedly elevated
free T4. Thyroid-stimulating immunoglobulins are positive. She is
started on methimazole.
Which mechanism best explains the underlying thyroid disorder?
A. Destruction of thyroid follicles by cytotoxic T lymphocytes
B. Antibodies that stimulate the TSH receptor
C. Autonomous activation of Gs proteins within thyroid follicular cells
D. Antibodies directed against thyroglobulin causing thyroid destruction
E. Excess hypothalamic production of thyrotropin-releasing hormone
Answer: B. Antibodies that stimulate the TSH receptor
Rationale: Graves disease is caused by thyroid-stimulating
immunoglobulins, which are IgG autoantibodies that bind and activate
the TSH receptor on thyroid follicular cells. This increases thyroid
hormone synthesis and gland growth. The suppressed TSH is a
consequence of negative feedback. Diffuse goiter and ophthalmopathy
strongly support Graves disease. Cytotoxic destruction is more
characteristic of Hashimoto thyroiditis.
1
,Question 2
A 67-year-old man with a 50-pack-year smoking history develops
progressive painless hematuria. Urinalysis confirms numerous red blood
cells without significant proteinuria or casts. CT imaging demonstrates a
mass arising from the lateral wall of the urinary bladder. Cystoscopy
reveals a papillary lesion projecting into the bladder lumen.
Which histologic finding is most likely associated with this malignancy?
A. Keratin pearls
B. Gland formation containing mucin
C. Urothelial cells with nuclear atypia and papillary architecture
D. Sheets of small round blue cells with Homer Wright rosettes
E. Spindle cells arranged in fascicles with cigar-shaped nuclei
Answer: C. Urothelial cells with nuclear atypia and papillary
architecture
Rationale: The most common bladder malignancy is urothelial
carcinoma, which classically presents with painless gross hematuria.
Smoking is a major risk factor because carcinogens are excreted into
the urine and expose the urothelium. Papillary tumors project into the
bladder lumen and demonstrate atypical urothelial cells. Keratin
pearls suggest squamous carcinoma, while gland formation suggests
adenocarcinoma.
Question 3
A 58-year-old woman presents with severe substernal chest pressure
radiating to her left arm. ECG demonstrates ST-segment elevations in
leads II, III, and aVF. She undergoes urgent coronary angiography,
which reveals complete occlusion of the right coronary artery.
Which region of the myocardium is most likely ischemic?
2
,A. Anterior wall and interventricular septum
B. Lateral wall
C. Inferior wall
D. Posterior wall exclusively
E. High anterolateral wall
Answer: C. Inferior wall
Rationale: The right coronary artery most commonly supplies the
inferior myocardium through the posterior descending artery in a
right-dominant circulation. ST elevation in leads II, III, and aVF
indicates an inferior myocardial infarction. RCA occlusion can also
compromise the AV node and cause bradyarrhythmias because the AV
nodal artery commonly arises from the RCA.
Question 4
A 9-year-old boy develops periorbital edema and cola-colored urine 2
weeks after recovering from impetigo. Blood pressure is 150/95 mm Hg.
Urinalysis reveals dysmorphic RBCs and RBC casts. Serum complement
C3 is decreased.
Which renal finding is most likely present?
A. Linear IgG deposition along the glomerular basement membrane
B. Subepithelial immune complex humps
C. Mesangial IgA deposition
D. Diffuse podocyte foot-process effacement without immune deposits
E. Crescent formation caused by anti-neutrophil cytoplasmic antibodies
Answer: B. Subepithelial immune complex humps
Rationale: Poststreptococcal glomerulonephritis is an immune
complex–mediated nephritic syndrome occurring after infection with
nephritogenic strains of Streptococcus pyogenes. Immune complexes
produce granular deposition, including characteristic subepithelial
3
, humps on electron microscopy. Low C3 typically returns to normal
within several weeks. IgA nephropathy generally occurs within days of
an upper respiratory or gastrointestinal infection rather than after a
prolonged latent period.
Question 5
A 35-year-old woman has recurrent episodes of severe abdominal pain,
peripheral neuropathy, anxiety, and dark urine. She has previously
undergone several unnecessary abdominal surgeries because of
unexplained pain. During an episode, laboratory testing demonstrates
markedly increased urinary porphobilinogen.
Which enzyme deficiency is most likely responsible?
A. Ferrochelatase
B. ALA dehydratase
C. Porphobilinogen deaminase
D. Uroporphyrinogen decarboxylase
E. Coproporphyrinogen oxidase
Answer: C. Porphobilinogen deaminase
Rationale: Acute intermittent porphyria results from deficiency of
porphobilinogen deaminase, also called hydroxymethylbilane
synthase. It causes episodic neurovisceral symptoms including
abdominal pain, peripheral neuropathy, psychiatric symptoms, and
autonomic dysfunction. Urine may become dark after standing.
Attacks can be precipitated by drugs, fasting, alcohol, and hormonal
changes. Photosensitivity is absent.
Question 6
4
