A 31-year-old man with recent hepatitis B surface antigenaemia presents with weight loss, abdominal pain, hypertension, and mononeuritis multiplex. Renal function is declining. CT angiography shows multiple microaneurysms of the mesenteric arteries. Lung involvement is absent. What is the most likely diagnosis?

• A Granulomatosis with polyangiitis
• B Microscopic polyangiitis
• C Polyarteritis nodosa ✓
• D IgA vasculitis

Explanation

Polyarteritis nodosa is a necrotising arteritis of medium vessels strongly linked to hepatitis B, presenting with systemic features, hypertension from renal artery involvement, neuropathy, and characteristic microaneurysms on angiography. Its key discriminator is the absence of glomerulonephritis and lung disease. Microscopic polyangiitis affects small vessels, is ANCA associated, and causes pauci-immune glomerulonephritis. GPA has granulomas and cavitating lung lesions, and IgA vasculitis is a small vessel disease of skin, gut, joints, and glomeruli.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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