USMLE Step 1 Medical Subject Review:
Pathology CNS 2023/2024
12-year-old boy is prepubescent and has grown to over two meters tall. An MRI of his head reveals an
extrasellar mass. The boy's tall stature is MOST probably due to which of the following physiologic
processes? - ANSWER-pituitary adenoma secreting elevated growth hormone
55-year-old man has had emotional changes consisting of sexual disinhibition and emotional apathy. He
later has difficulty with expressing himself and doing his usual routine. The magnetic resonance imaging
(MRI) reveals atrophy of the frontal and temporal lobes, along with swollen neurons in the temporal and
frontal areas of the brain, and intraneuronal argentophilic inclusion bodies in these same areas. What
type of dementia is this patient exhibiting? - ANSWER-Dementia due to Pick's disease
69-year-old woman suffered a massive stroke 6 weeks ago. She is now recovering from the stroke, but
she has residual paralysis and sensory impairment of her right arm. She is also unable to speak and
unable to turn her eyes to the right. The most likely site of her lesion is in the area that is supplied by
what artery? - ANSWER-Left middle cerebral artery
65-year-old woman has a long-standing dementing disorder characterized by deterioration in
personality, neglect of personal hygiene, impaired judgment, and uninhibited behavior. MRI
demonstrates severe cortical atrophy limited to the frontal lobes and anterior two thirds of the temporal
lobes, while the remaining cortex is preserved. No evidence of recent or remote infarcts is found. What
diagnosis is most consistent with these pathologic and clinical features? - ANSWER-Frontotemporal
dementia
53-year-old man presents with a 2-week history of severe headaches that occur primarily at night. The
patient is pacing while he is talking. The pain surrounds one eye and lasts for 30-90 minutes. He also
states that there is ipsilateral lacrimation, conjunctival injection, and nasal congestion during the attacks.
The patient states that he has had these headaches once a day over the last week. He cannot point to
any one thing that causes them. On examination, the patient has features of partial Horner's syndrome.
His vital signs are temperature: 97.0°F, heart rate: 80/min, respiration 16/min, and blood pressure:
126/80 mm Hg. What is the most likely diagnosis? - ANSWER-Cluster headache
,3-year-old girl shows a white reflection from the surface of the retina upon ophthalmologic examination.
Biopsy of the lesion reveals retinoblastoma (Rb). Underphosphorylated Rb gene product has which
significant characteristic? - ANSWER-prevents mitosis
38-year-old man with uncontrolled facial movements states that he has noticed himself over the last few
months making expressions without even realizing it or being able to control it. Further questioning
reveals that he also has noted an inability to intentionally move his eyes quickly without blinking. Very
recently, he noted an inability to sustain physical movements, such as grasping objects with his hands.
Physical examination reveals a puppet-like gait and obvious chorea. The patient admits that he does not
know anything about his family history due to the fact that he was adopted when he was 4. Based on the
history and physical examination findings, what is the most likely diagnosis? - ANSWER-Huntington's
disease
54-year-old white male presents with gradual onset of mild dementia, ataxic gait, and startle myoclonus.
An MRI scan is normal, and an examination of his cerebrospinal fluid reveals no abnormalities, but the
patient's EEG is remarkable for recurrent bursts of high-voltage slow waves. Over the next 6 months, the
patient's dementia rapidly worsens, accompanied by general hypertonicity and profound dysarthria. The
patient dies shortly thereafter. What is the most likely neuropathological finding on autopsy? - ANSWER-
Diffuse spongiform change
35-year-old woman presents with proptosis and diminishing vision in her right eye. Magnetic resonance
imaging demonstrated a well-demarcated, globular mass arising from the optic nerve. Microscopic
examination of the enucleated mass shows cells with nuclei having finely dispersed chromatin and
inconspicuous nucleus. The cells have poorly defined borders forming whorls around vessels and stromal
elements. What is the most likely diagnosis? - ANSWER-Meningioma
35-year-old woman with Down syndrome (trisomy 21) is brought in by her family. Previously, she had
learned to read street signs and write her name. Until a year ago, she attended a sheltered workshop
where she sorted color coded components for appliance repair. In the past year, she has become more
impaired and can no longer reliably recognize people she does not see every day. She is no longer able to
dress herself, and she is unable to work. On mental status examination, she is pleasant but distracted,
and she is oriented to person only. Her speech is grammatically fragmented and dysarthric. She cannot
remember what she ate for lunch an hour before. She does not recognize a picture of a stop sign. What
is the most likely diagnosis? - ANSWER-Dementia of the Alzheimer type
72-year-old man exhibits progressive tremors, bradykinesia, and muscular rigidity. He is slow to initiate
movements and shows other motor abnormalities. The most likely diagnosis of his disease is which of
the following conditions? - ANSWER-Parkinson disease
, A CT-scan of a patient reveals damage to the medulla oblongata in the region supplied by the posterior
inferior cerebellar artery. The neurologist concludes that the patient has a classic Wallenberg (lateral
medullary) syndrome. The patient would show dysphagia and dysarthria due to which of the following? -
ANSWER-destruction of the nucleus ambiguus
64-year-old man with a medical history of hypertension and diabetes mellitus presents because his wife
is concerned that he is losing his memory. She states it might have all started when he had a stroke 1
year ago. He began to have difficulty remembering where his glasses are and difficulty going to the store
to pick up groceries. The patient had seemingly improved, but a few months later he began to have
increased difficulty following instructions, mood swings, and problems handling money. The patient does
not report aphasia, incontinence, problems with gait, or weakness. Vital signs are T 99.2°F, BP
140/94mm Hg, P 98/min, and R 14/min. TSH, B12, serum electrolytes, and fasting glucose are within
normal limits. What is the most likely pathogenesis of this patient's disease? - ANSWER-Multiple small
cerebral infarctions
35-year-old, sexually active woman misses her period. She takes a home pregnancy test, but it is
negative. She does not worry about it and attributes it to stress. She has been under a lot of pressure at
work lately and has had headaches that she also attributes to stress. However, she misses her next
period and the one after that as well. She notices that she has milk discharge from her breasts and
becomes quite concerned that she might be pregnant. She buys another home pregnancy test, and again
the test is negative. She sees her OB-GYN. On questioning during the medical history, she comments that
up until a few months ago her periods had been every 28 days. Several blood tests are done. Her results
are in the chart.
TEST
RESULTS
REFERENCE RANGE
Urine beta hCG
Negative
Negative
Serum beta hCG
Negative
Negative
Prolactin
312 ng/mL
