Welcome back to MedSmarter’s USMLE Style Question of the Week. Here’s the breakdown of another high-yield Pathology question for those preparing for your USMLE Step 1 or just to gain some knowledge. As always you want to begin by 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:
A 44-year-old man presents to his physician with numbness and tingling on the dorsal surface of his right hand and forearm and raised “varicose veins” that are firm to the touch along the same distribution. He also complains of weight loss. He has no previous medical history of significance. Lab values show his serum creatinine level is 2.3 mg/dL. An immune complex disease is suspected, and assays for autoantibodies in neutrophils are conducted. What diseases are associated with the identification of anti-myeloperoxidase and anti-proteinase-3 antibodies, respectively?
A) Temporal arteritis, Wegener’s granulomatosis
B) Kawasaki’s disease, Buerger’s disease
C) Microscopic polyangiitis, Wegener’s granulomatosis
D) Polyarteritis nodosa, Buerger’s disease
E) Takayasu’s arteritis, Wegener’s granulomatosis
The correct answer choice is C. On the other hand, anti-myeloperoxidase antibodies are associated with two vasculitides, microscopic polyangiitis, and Churg-Strauss syndrome. Churg-Strauss syndrome is characterized by asthma, eosinophilia, and granulomatous inflammation, which are not mentioned in the vignette. Therefore, the most likely diagnosis, in this case, is microscopic polyangiitis, which is associated with the presence of perinuclear antineutrophil cytoplasmic antibodies (p-ANCA), also known as anti-myeloperoxidase antibodies. This information allows us to eliminate answer choices A, B, D, and E, leaving us with answer choice C as the correct answer.
Did you think the answer was different?
Did you think that the correct answer choice was other than C? You can view this video for a deeper discussion of why A, B, D, and E are not the correct answer choices.
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