Warfarin induced leukocytoclastic vasculitis: an extraordinary side effect

Area of Science:

• Hematology
• Dermatology
• Pharmacology

Background:

• Warfarin is a widely prescribed anticoagulant for thromboembolic disorders.
• Rheumatic heart disease and mechanical heart valves are common indications for anticoagulation therapy.

Observation:

• A patient with a mechanical mitral valve presented with heart failure and palpable purpura.
• Skin lesions improved upon warfarin withdrawal due to elevated INR.
• Re-challenge with warfarin reproduced the skin lesions, confirming drug-induced vasculitis.

Findings:

• Skin biopsy revealed leukocytoclastic vasculitis with eosinophilic infiltration.
• Drug hypersensitivity accounts for a third of leukocytoclastic vasculitis cases.
• Warfarin was identified as the causative agent in this rare adverse drug event.

Implications:

• Clinicians should maintain a high index of suspicion for drug-induced vasculitis, a diagnosis of exclusion.
• Early discontinuation of the offending drug is critical.
• Prompt initiation of anti-inflammatory or immunosuppressive therapy may be necessary to prevent severe outcomes and mortality.