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Drug-Induced LCV — RACP Adult Medicine MCQ

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ModerateDermatologyDrug-Induced LCVRACP Adult Medicine

A 50-year-old woman develops a rash on her legs 14 days after commencing trimethoprim for a UTI. Examination shows palpable purpura predominantly on the lower extremities. Biopsy shows leucocytoclastic vasculitis with perivascular neutrophilic infiltrate and fibrinoid necrosis. What is the most likely type of vasculitis?

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Correct answer: B — Drug-induced cutaneous small vessel vasculitis

Palpable purpura on the lower extremities with leucocytoclastic vasculitis (LCV) on biopsy occurring 1–3 weeks after drug exposure is classic for drug-induced cutaneous small vessel vasculitis. Common culprits include antibiotics (trimethoprim, penicillins, cephalosporins), NSAIDs, and allopurinol. Management involves cessation of the offending drug. Most cases resolve within weeks. If renal, GI, or other organ involvement is present, a more detailed vasculitis workup (ANCA, complement, cryoglobulins) is required.

Reference: eTG – 2025 – Dermatology; eTG – 2025 – Rheumatology