PTU-associated cutaneous vasculitis with ANCA anti-MPO and anti-PR3 antibodies.

A 36-year-old woman presented at our clinic with symmetrical, tender, palpable purpuric lesions on her lower legs and buttocks after restarting PTU therapy for relapsing Graves' disease. PTU-induced vasculitis was diagnosed with remarkable ANCA anti-MPO and anti-PR3 antibody positivity. The purpuric skin lesions resolved immediately after discontinuation of the drug and the ANCA titres lowered. In the presence of activated neutrophils, PTU could induce a high cytotoxity and injure the vessel walls. Treatment of choice is discontinuation of the drug. Sometimes more aggressive therapy as cyclophosphamide or plasmapheresis is warranted.