Adult-Onset IgA Vasculitis Initially Attributed to a Cutaneous Drug Reaction and Diverticulitis

Immunoglobulin A vasculitis (IgAV), formerly Henoch–Schönlein purpura, is a small-vessel vasculitis characterized by palpable purpura, arthralgias, gastrointestinal involvement, and renal disease. Although IgAV is common in children, adult-onset disease is rare and may be associated with more severe manifestations, particularly renal involvement. In adults, IgAV may be difficult to recognize because of overlap with more common gastrointestinal, infectious, or medication-related conditions. We present a case of adult-onset IgAV initially attributed to presumed diverticulitis and later to a drug eruption following antibiotic exposure. This case highlights diagnostic pitfalls and the importance of early recognition and renal surveillance.