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USMLE Clinical Cases: Pituitary Adenoma, Acromegaly and Schizophrenia
These 3 detailed USMLE clinical case questions cover two pituitary cases and one psychiatry case that are tested again and again: the visual field defect of a pituitary adenoma, the best first test for acromegaly, and how to tell schizophrenia apart from other psychotic disorders. Each case has a full explanation.
Written by Dr. Ray Makar, MD, author of the Repeated USMLE Questions eBook series.
How to use this page: read the question, pick your answer, then tap Show Answer and Explanation.
Questions
Question 1. A 34-year-old woman visits her physician with a complaint of severe headache for two months. She took several kinds of analgesics with no significant improvement. Her headache is worse in the morning and improved by doing day activities. Imaging studies and laboratory tests confirm the diagnosis of pituitary adenoma. Which of the following is the most likely effect of this tumor on vision?
The pituitary gland is located just below the optic chiasm, where the nasal (medial) retinal fibers from both eyes cross. A pituitary adenoma can compress the optic chiasm, leading to loss of vision in the temporal (lateral) visual fields of both eyes, a condition known as bitemporal hemianopsia.
Homonymous hemianopsia occurs with lesions posterior to the optic chiasm (e.g., stroke or tumors affecting the optic tract, lateral geniculate body, or occipital lobe). It causes visual loss in the same side of both eyes (e.g., right homonymous hemianopsia = loss of right visual field in both eyes).
Binasal hemianopsia is rare and usually caused by bilateral lateral compression of the optic chiasm (e.g., from calcified carotid arteries). A pituitary adenoma does not typically cause this pattern.
Superior hemianopsia occurs in specific optic radiation lesions, such as temporal lobe lesions affecting Meyer’s loop, leading to a superior quadrantanopia (“pie in the sky” defect). Pituitary adenomas do not cause this type of visual loss.
The correct answer is C
Question 2. A 54-year-old woman with a 6-year history of type 2 diabetes visits her physician for a regular examination. She was initially treated with oral hypoglycemic but her HbA1c had gotten worse so, her physician switched to insulin last year. Six-month ago, she had surgery in her wrist to release compression caused by carpal tunnel syndrome. Now, she complains of progressive increase in her feet size. Examination reveals coarse facial features with prominent supraorbital ridge. What is the most appropriate test to help reach the diagnosis of this case?
A- Assessment of insulin-like growth factor 1 (IGF-1)
B- Measurement of thyroid stimulating hormone (TSH)
C- Measurement of HbA1c
D- Fasting serum glucose test
E- Dexamethasone suppression test
This is a case of acromegaly due to increased secretion of growth hormone. Insulin-like growth factor 1 is secreted by the liver in response to high level of growth hormone. High levels of IGF-1 support the diagnosis of acromegaly. CT scan of the head and/or MRI of the brain should follow to find the cause which could be pituitary adenoma or hyperplasia. Fasting serum glucose test and HbA1c should be done routinely but they have no rule in diagnosis of the new condition. There is no clue for thyroid or adrenal gland involvement in this case so other choices are incorrect.
The correct answer is A
Question 3. A 36-year-old man presents to the emergency room asking for the removal of software implanted in his body by his neighbor. He tells you that his ex-wife is hiring this neighbor to spy on him. For the last 6 years, he has been hearing them talking about him and all the details of his life. He lives alone and he does not have any friends. He has no kids and one sister who does not visit him anymore since he accused her of spying on him. His physical examination and laboratory studies are unremarkable. A drug test is negative. What is the most likely diagnosis?
The presentation suggests the presence of delusions (believing that the neighbor implanted software in his body to spy on him) and possible auditory hallucinations (hearing the neighbor and ex-wife talking about him), along with social withdrawal and impaired relationships with family members. These symptoms are indicative of a psychotic disorder.
Given the duration of symptoms (6 years) and the absence of mood episodes (such as mania or depression) described in the scenario, bipolar disorder and major depressive disorder are less likely.
Schizophrenia involves the presence of delusions, hallucinations, disorganized thinking, and other psychotic symptoms lasting for at least 6 months, which aligns with this patient’s presentation. However, the duration of symptoms in this case does not meet the criterion for a schizophrenia diagnosis.
Brief psychotic disorder is characterized by the sudden onset of psychotic symptoms, such as delusions, hallucinations, disorganized speech, or grossly disorganized or catatonic behavior, lasting for at least 1 day but less than 1 month, with eventual return to premorbid functioning. However, the duration of symptoms in this case exceeds the time frame for brief psychotic disorder.
Schizophreniform disorder shares similar symptoms with schizophrenia but has a shorter duration, with symptoms lasting between 1 to 6 months. Given the duration of symptoms in this case (6 years), schizophreniform disorder is less likely.
The correct answer is D
High-yield points from this set
A pituitary adenoma compresses the optic chiasm and causes bitemporal hemianopsia.
Acromegaly is screened with serum IGF-1; confirm with failure of growth hormone suppression after an oral glucose load.
Delusions and hallucinations for more than 6 months with social decline = schizophrenia (1–6 months = schizophreniform; less than 1 month = brief psychotic disorder).