warfarin induced leukocytoclastic vasculitis: an extraordinary side effect

Warfarin is one of the most commonly used anticoagulants in the management of thromboembolic events. herein we report a rare case of warfarin induced leukocytoclastic vasculitis in a patient with history of rheumatic heart disease and a mechanical mitral valve prosthesis who presented with heart failure and palpable purpura. upon clinical suspicion of cutaneous small vessel vasculitis, a comprehensive laboratory panel was performed. warfarin induced vasculitis was suspected when withdrawal of warfarin, due to rising inr, led to improvement of the skin lesions. the diagnosis was finally confirmed when re-instatement of warfarin reproduced the skin lesions and a skin biopsy showed evidence for leukocytoclastic vasculitis with eosinophilic infiltration. a third of cases of leukocytoclastic vasculitis are due to drug hypersensitivity which being a diagnosis of exclusion with varying manifestations, requires a high index of clinical suspicion. since drug induced leukocytoclastic vasculitis affect multiple organ systems and even cause mortality, clinicians must be aware of this rare adverse event, promptly discontinue the drug, and commence anti-inflammatory or immunosuppressive treatment when necessary.