Which statement best describes a key pathologic feature of polyarteritis nodosa?

• A. Immune complex deposition with eosinophilic infiltration in small capillaries
• B. Necrotizing granulomas in bronchovascular spaces
• C. Immune complex deposition with fibrinoid necrosis in medium-sized arteries
• D. Lymphocytic vasculitis of the capillaries

Answer: (D)

Medium-sized arteries with transmural, necrotizing inflammation and fibrinoid necrosis are the hallmark of polyarteritis nodosa. This immune-mediated process damages the arterial wall, can cause aneurysms, and often spares the lungs. The description that emphasizes immune complex deposition with fibrinoid necrosis in medium-sized arteries best captures this pattern and aligns with PAN’s typical pathophysiology.

In contrast, events described as lymphocytic vasculitis of capillaries reflect small-vessel involvement rather than medium-sized arteries, and aren’t the classic PAN feature. Necrotizing granulomas in bronchovascular spaces point to granulomatosis with polyangiitis, which has granulomatous inflammation in the respiratory tract. Immune complex deposition with eosinophilic infiltration in small capillaries suggests a different small-vessel vasculitis, not PAN.