A case of probable trimethoprim-sulfamethoxazole induced circulating antineutrophil cytoplasmic antibody-positive small vessel vasculitis

Abstract

Cutaneous leukocytoclastic vasculitis can occur as skin-limited disease or as part of systemic vasculitis. Appropriate workup includes the evaluation of antineutrophil cytoplasmic antibodies (ANCAs), with a positive titer raising concern for the associated primary vasculitides including microscopic polyangiitis, granulomatosis with polyangiitis, or eosinophilic granulomatosis with polyangiitis. In the absence of systemic findings, however, a drug etiology must also be considered. Tumor necrosis factor inhibitors, propylthiouracil, levamisole-adulterated cocaine, hydralazine, and minocycline have been previously documented to induce ANCA-positive vasculitis (APV), which may present with conspicuously high ANCA titers. Herein we report trimethoprim-sulfamethoxazole as another culprit in drug-induced APV. Our case reinforces the need to consider drug etiology for APV and cautions against interpreting positive ANCAs as equivalent to evidence of systemic disease.