Welcome to MedSmarter’s USMLE Style Question Break Down of the Week. For those preparing for the USMLE Step 1, this week we break down a high-yield Pathology question. As always you want to begin with reading the last sentence of the vignette first to get an understanding of what the question is asking for.
Question Break Down of the Week:
After a 65-year-old man with a progressive, chronic movement disorder dies, the family requests an autopsy. On gross inspection of the patient’s brain, the pathologist notes the presence of a deep brain stimulator electrode. The pathologist then obtains a tissue specimen of the basal ganglia for histologic analysis (see image) that stains positive for α-synuclein. From which disease did the decedent most likely suffer?
A) Huntington’s disease
B) Guillain-Barré syndrome
C) Pick’s disease
D) Werdnig-Hoffman disease
E) Parkinson’s disease
The correct answer choice is E: The tissue section shown demonstrates a Lewy body, which is a cytoplasmic inclusion consisting of aggregated α-synuclein, tubulin, ubiquitin, and neurofilament proteins. Lewy bodies present in the substantia nigra, in the context of a movement disorder (evidenced by this patient’s history and the presence of a deep brain stimulator), are highly suggestive of Parkinson’s disease. The Lewy body is believed to result from disrupted proteasomal activity, leading to the accumulation of cellular proteins, which results in the disruption of normal cellular processes.
Did you think the answer was different?
Did you think that the correct answer choice was other than E? You can view this video for a deeper discussion of why A, B, C, and D are not the correct answer choices.
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