COMSAE Phase 1 Form 113 Practice Exam
Questions And Well Graded Solutions With
Rationales Updated 2026-2027
Master your board preparation with this premium study guide for the NBOME COMSAE Phase
1 Form 113 exam [1]. This comprehensive bundle features real practice questions paired with
verified, high-yield answers and detailed rationales covering anatomy, microbiology, and OMM
[1]. Perfect for OMS-II students tracking milestones to hit school-mandated score thresholds
and clear the COMLEX-USA Level 1 hurdle with absolute confidence. Secure the ultimate
medical board study resource today!
Question 1
A 24-year-old medical student presents with a painful rash on his wrist. He reports
spending the weekend hiking in a heavily wooded area. Physical examination
reveals an erythematous, linear vesicular eruption. This clinical presentation is
mediated by which of the following hypersensitivity mechanisms?
A) Type I
B) Type II
C) Type III
D) Type IV
Rationale: Contact dermatitis from poison ivy (urushiol) is a classic example of a
Type IV (delayed-type) hypersensitivity reaction. It is mediated by T-lymphocytes
rather than antibodies, typically taking 24 to 48 hours to manifest after allergen
exposure.
Question 2
A 65-year-old male presents with a persistent cough and weight loss. Imaging
reveals a central lung mass. Laboratory results demonstrate a serum calcium level of
12.5 mg/dL. Which of the following is the most likely histological diagnosis?
A) Adenocarcinoma
B) Small cell carcinoma
C) Squamous cell carcinoma
D) Large cell carcinoma
Rationale: Squamous cell lung carcinoma is traditionally associated with a central
location, a history of smoking, and paraneoplastic production of parathyroid
hormone-related peptide (PTHrP), which causes hypercalcemia.
Question 3
An 8-month-old infant is brought to the clinic due to severe developmental delay and
a musty body odor. A screening test indicates an inability to convert phenylalanine to
tyrosine. Which of the following amino acids becomes essential in this patient?
A) Alanine
B) Glycine
C) Tryptophan
D) Tyrosine
,Rationale: In phenylketonuria (PKU), the enzyme phenylalanine hydroxylase is
deficient. Because phenylalanine cannot be converted to tyrosine, tyrosine becomes
an essential amino acid that must be supplied in the diet.
Question 4
A 45-year-old female presents with fatigue and cold intolerance. Physical
examination reveals a diffuse, painless enlargement of the thyroid gland. Serum
studies show elevated thyroid-stimulating hormone (TSH) and low free T4. Biopsy
shows intense lymphocytic infiltrate with Hurthle cells. What is the most likely
diagnosis?
A) Graves disease
B) Hashimoto thyroiditis
C) Subacute granulomatous thyroiditis
D) Papillary thyroid carcinoma
Rationale: Hashimoto thyroiditis is the most common cause of hypothyroidism in
iodine-sufficient areas. It is characterized histologically by a lymphocytic infiltrate,
germinal centers, and Hurthle cells (epitheloid cells with eosinophilic cytoplasm).
Question 5
During an osteopathic structural examination, a physician notes that a patient's T4
vertebrae rotates easily to the right but resists rotation to the left. Sidebending is
found to be restricted to the right. Which of the following correctly describes this
somatic dysfunction?
A) T4 Rotated Right, Sidebent Left
B) T4 Rotated Left, Sidebent Right
C) T4 Rotated Right, Sidebent Right
D) T4 Rotated Left, Sidebent Left
Rationale: Somatic dysfunctions are named for their position of comfort (the direction
in which they move easily). Since the vertebra rotates easily to the right, it is Rotated
Right (RR). Because it resists sidebending to the right, it prefers moving to the left,
making it Sidebent Left (SL).
Question 6
A 32-year-old pregnant female at 28 weeks gestation presents with universal
pruritus, particularly on the palms and soles, which worsens at night. Lab work
reveals elevated serum bile acids. Which of the following is the most appropriate
first-line pharmacotherapy?
A) Cholestyramine
B) Diphenhydramine
C) Ursodeoxycholic acid
D) Prednisone
Rationale: Intrahepatic cholestasis of pregnancy presents with intense pruritus
involving the palms and soles due to elevated bile acids. Ursodeoxycholic acid is the
first-line treatment as it decreases serum bile acid concentrations and improves fetal
outcomes.
,Question 7
A 54-year-old male with a history of chronic alcoholism presents to the emergency
department with severe epigastric pain radiating to his back, accompanied by
nausea and vomiting. Laboratory studies show significantly elevated serum lipase.
What is the primary pathophysiological mechanism behind this condition?
A) Premature activation of trypsinogen
B) Ischemic necrosis of the mesenteric vessels
C) Retrograde flow of bile into the stomach
D) Autoimmune destruction of islet cells
Rationale: Acute pancreatitis, frequently triggered by alcohol use or gallstones,
involves the inappropriate intra-acinar activation of trypsinogen to trypsin. This leads
to the enzymatic autodigestion of the pancreatic parenchyma.
Question 8
A 19-year-old college student presents with a high fever, severe headache, and neck
stiffness. A lumbar puncture is performed, and cerebrospinal fluid (CSF) analysis
reveals increased neutrophils, decreased glucose, and elevated protein. Gram stain
shows Gram-negative diplococci. Which organism is responsible?
A) Streptococcus pneumoniae
B) Haemophilus influenzae
C) Neisseria meningitidis
D) Listeria monocytogenes
Rationale: Neisseria meningitidis is a Gram-negative diplococcus that commonly
causes bacterial meningitis in young adults living in close quarters. The CSF profile
reveals an elevated neutrophil count, low glucose, and high protein.
Question 9
A 60-year-old male presents with resting tremors, bradykinesia, and a shuffling gait.
The primary pathology of this disease involves the loss of dopaminergic neurons in
which of the following brain regions?
A) Caudate nucleus
B) Putamen
C) Substantia nigra pars compacta
D) Subthalamic nucleus
Rationale: Parkinson's disease is characterized by the degeneration of dopaminergic
neurons within the substantia nigra pars compacta of the basal ganglia, leading to a
loss of voluntary movement control.
Question 10
A 3-year-old boy is brought to the pediatrician because his mother noticed he uses
his hands to "climb up" his own legs to stand up from a sitting position. Genetic
testing confirms a mutation in the gene encoding dystrophin. What is the mode of
inheritance for this condition?
, A) Autosomal dominant
B) Autosomal recessive
C) X-linked recessive
D) X-linked dominant
Rationale: Duchenne muscular dystrophy is an X-linked recessive disorder
characterized by a mutation in the dystrophin gene. The sign described is Gowers'
sign, indicating proximal muscle weakness.
Question 11
A 50-year-old male with chronic hypertension presents with a sudden onset of
tearing chest pain radiating to his back. A chest X-ray reveals a widened
mediastinum. Which of the following vascular layers is primarily torn to create a false
lumen in this condition?
A) Tunica intima
B) Tunica media
C) Tunica adventitia
D) Internal elastic lamina
Rationale: Aortic dissection occurs when an intimal tear allows blood to track into
and dissect the tunica media of the aortic wall, establishing a false lumen.
Question 12
A 22-year-old male presents with a painless, hard nodule on his left testicle. An
ultrasound confirms a solid mass. Serum markers reveal elevated beta-hCG but
normal alpha-fetoprotein (AFP). What is the most likely diagnosis?
A) Yolk sac tumor
B) Choriocarcinoma
C) Teratoma
D) Leydig cell tumor
Rationale: Choriocarcinoma is a highly aggressive testicular germ cell tumor
characterized by a marked elevation of beta-hCG. It does not characteristically
elevate AFP, unlike yolk sac tumors.
Question 13
A 68-year-old female presents with sudden, painless loss of vision in her right eye.
Fundoscopic examination reveals a pale retina with a distinct "cherry-red spot" at the
macula. Which of the following is the most likely diagnosis?
A) Central retinal vein occlusion
B) Central retinal artery occlusion
C) Retinal detachment
D) Acute angle-closure glaucoma
Rationale: Central retinal artery occlusion presents with sudden, painless monocular
vision loss. The classic fundoscopic finding is a pale, ischemic retina with a
prominent cherry-red spot at the macula due to preserved ciliary artery perfusion.
Question 14
Questions And Well Graded Solutions With
Rationales Updated 2026-2027
Master your board preparation with this premium study guide for the NBOME COMSAE Phase
1 Form 113 exam [1]. This comprehensive bundle features real practice questions paired with
verified, high-yield answers and detailed rationales covering anatomy, microbiology, and OMM
[1]. Perfect for OMS-II students tracking milestones to hit school-mandated score thresholds
and clear the COMLEX-USA Level 1 hurdle with absolute confidence. Secure the ultimate
medical board study resource today!
Question 1
A 24-year-old medical student presents with a painful rash on his wrist. He reports
spending the weekend hiking in a heavily wooded area. Physical examination
reveals an erythematous, linear vesicular eruption. This clinical presentation is
mediated by which of the following hypersensitivity mechanisms?
A) Type I
B) Type II
C) Type III
D) Type IV
Rationale: Contact dermatitis from poison ivy (urushiol) is a classic example of a
Type IV (delayed-type) hypersensitivity reaction. It is mediated by T-lymphocytes
rather than antibodies, typically taking 24 to 48 hours to manifest after allergen
exposure.
Question 2
A 65-year-old male presents with a persistent cough and weight loss. Imaging
reveals a central lung mass. Laboratory results demonstrate a serum calcium level of
12.5 mg/dL. Which of the following is the most likely histological diagnosis?
A) Adenocarcinoma
B) Small cell carcinoma
C) Squamous cell carcinoma
D) Large cell carcinoma
Rationale: Squamous cell lung carcinoma is traditionally associated with a central
location, a history of smoking, and paraneoplastic production of parathyroid
hormone-related peptide (PTHrP), which causes hypercalcemia.
Question 3
An 8-month-old infant is brought to the clinic due to severe developmental delay and
a musty body odor. A screening test indicates an inability to convert phenylalanine to
tyrosine. Which of the following amino acids becomes essential in this patient?
A) Alanine
B) Glycine
C) Tryptophan
D) Tyrosine
,Rationale: In phenylketonuria (PKU), the enzyme phenylalanine hydroxylase is
deficient. Because phenylalanine cannot be converted to tyrosine, tyrosine becomes
an essential amino acid that must be supplied in the diet.
Question 4
A 45-year-old female presents with fatigue and cold intolerance. Physical
examination reveals a diffuse, painless enlargement of the thyroid gland. Serum
studies show elevated thyroid-stimulating hormone (TSH) and low free T4. Biopsy
shows intense lymphocytic infiltrate with Hurthle cells. What is the most likely
diagnosis?
A) Graves disease
B) Hashimoto thyroiditis
C) Subacute granulomatous thyroiditis
D) Papillary thyroid carcinoma
Rationale: Hashimoto thyroiditis is the most common cause of hypothyroidism in
iodine-sufficient areas. It is characterized histologically by a lymphocytic infiltrate,
germinal centers, and Hurthle cells (epitheloid cells with eosinophilic cytoplasm).
Question 5
During an osteopathic structural examination, a physician notes that a patient's T4
vertebrae rotates easily to the right but resists rotation to the left. Sidebending is
found to be restricted to the right. Which of the following correctly describes this
somatic dysfunction?
A) T4 Rotated Right, Sidebent Left
B) T4 Rotated Left, Sidebent Right
C) T4 Rotated Right, Sidebent Right
D) T4 Rotated Left, Sidebent Left
Rationale: Somatic dysfunctions are named for their position of comfort (the direction
in which they move easily). Since the vertebra rotates easily to the right, it is Rotated
Right (RR). Because it resists sidebending to the right, it prefers moving to the left,
making it Sidebent Left (SL).
Question 6
A 32-year-old pregnant female at 28 weeks gestation presents with universal
pruritus, particularly on the palms and soles, which worsens at night. Lab work
reveals elevated serum bile acids. Which of the following is the most appropriate
first-line pharmacotherapy?
A) Cholestyramine
B) Diphenhydramine
C) Ursodeoxycholic acid
D) Prednisone
Rationale: Intrahepatic cholestasis of pregnancy presents with intense pruritus
involving the palms and soles due to elevated bile acids. Ursodeoxycholic acid is the
first-line treatment as it decreases serum bile acid concentrations and improves fetal
outcomes.
,Question 7
A 54-year-old male with a history of chronic alcoholism presents to the emergency
department with severe epigastric pain radiating to his back, accompanied by
nausea and vomiting. Laboratory studies show significantly elevated serum lipase.
What is the primary pathophysiological mechanism behind this condition?
A) Premature activation of trypsinogen
B) Ischemic necrosis of the mesenteric vessels
C) Retrograde flow of bile into the stomach
D) Autoimmune destruction of islet cells
Rationale: Acute pancreatitis, frequently triggered by alcohol use or gallstones,
involves the inappropriate intra-acinar activation of trypsinogen to trypsin. This leads
to the enzymatic autodigestion of the pancreatic parenchyma.
Question 8
A 19-year-old college student presents with a high fever, severe headache, and neck
stiffness. A lumbar puncture is performed, and cerebrospinal fluid (CSF) analysis
reveals increased neutrophils, decreased glucose, and elevated protein. Gram stain
shows Gram-negative diplococci. Which organism is responsible?
A) Streptococcus pneumoniae
B) Haemophilus influenzae
C) Neisseria meningitidis
D) Listeria monocytogenes
Rationale: Neisseria meningitidis is a Gram-negative diplococcus that commonly
causes bacterial meningitis in young adults living in close quarters. The CSF profile
reveals an elevated neutrophil count, low glucose, and high protein.
Question 9
A 60-year-old male presents with resting tremors, bradykinesia, and a shuffling gait.
The primary pathology of this disease involves the loss of dopaminergic neurons in
which of the following brain regions?
A) Caudate nucleus
B) Putamen
C) Substantia nigra pars compacta
D) Subthalamic nucleus
Rationale: Parkinson's disease is characterized by the degeneration of dopaminergic
neurons within the substantia nigra pars compacta of the basal ganglia, leading to a
loss of voluntary movement control.
Question 10
A 3-year-old boy is brought to the pediatrician because his mother noticed he uses
his hands to "climb up" his own legs to stand up from a sitting position. Genetic
testing confirms a mutation in the gene encoding dystrophin. What is the mode of
inheritance for this condition?
, A) Autosomal dominant
B) Autosomal recessive
C) X-linked recessive
D) X-linked dominant
Rationale: Duchenne muscular dystrophy is an X-linked recessive disorder
characterized by a mutation in the dystrophin gene. The sign described is Gowers'
sign, indicating proximal muscle weakness.
Question 11
A 50-year-old male with chronic hypertension presents with a sudden onset of
tearing chest pain radiating to his back. A chest X-ray reveals a widened
mediastinum. Which of the following vascular layers is primarily torn to create a false
lumen in this condition?
A) Tunica intima
B) Tunica media
C) Tunica adventitia
D) Internal elastic lamina
Rationale: Aortic dissection occurs when an intimal tear allows blood to track into
and dissect the tunica media of the aortic wall, establishing a false lumen.
Question 12
A 22-year-old male presents with a painless, hard nodule on his left testicle. An
ultrasound confirms a solid mass. Serum markers reveal elevated beta-hCG but
normal alpha-fetoprotein (AFP). What is the most likely diagnosis?
A) Yolk sac tumor
B) Choriocarcinoma
C) Teratoma
D) Leydig cell tumor
Rationale: Choriocarcinoma is a highly aggressive testicular germ cell tumor
characterized by a marked elevation of beta-hCG. It does not characteristically
elevate AFP, unlike yolk sac tumors.
Question 13
A 68-year-old female presents with sudden, painless loss of vision in her right eye.
Fundoscopic examination reveals a pale retina with a distinct "cherry-red spot" at the
macula. Which of the following is the most likely diagnosis?
A) Central retinal vein occlusion
B) Central retinal artery occlusion
C) Retinal detachment
D) Acute angle-closure glaucoma
Rationale: Central retinal artery occlusion presents with sudden, painless monocular
vision loss. The classic fundoscopic finding is a pale, ischemic retina with a
prominent cherry-red spot at the macula due to preserved ciliary artery perfusion.
Question 14
