Propylthiouracil-Induced Skin Vasculitis

The use of propylthiouracil (PTU) is associated with the development of autoantibodies, namely, antineutrophil cytoplasmic antibodies (ANCAs), which are associated with the pathogenesis of ANCA-associated systemic vasculitis, most often related to the myeloperoxidase subtype (ANCA-MPO). The authors report the case of a 61-year-old woman on PTU for one year who was referred to Internal Medicine for a three-month evolution of painless non-blanching purple patches, non-pruriginous, involving the chest and legs. The autoimmunity revealed ANCA antibody positivity, with a cutaneous biopsy compatible with leukocytoclastic vasculitis/necrotizing vasculitis with involvement of small and medium-sized vessels. Clinical improvement was noted after the drug was discontinued, with the resolution of the analytical changes.