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Warfarin Skin Necrosis — SCE Dermatology MCQ

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HardDrug ReactionsWarfarin Skin NecrosisSCE Dermatology

A 42-year-old woman develops painful necrotic skin lesions on her thighs 4 days after starting therapeutic anticoagulation with Warfarin. She has no history of skin disease. Protein C level (taken before Warfarin initiation) was low. Which statement about the pathophysiology is correct?

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Correct answer: A — Warfarin depletes protein C (short half-life) before procoagulant factors causing a transient hypercoagulable state

Warfarin necrosis occurs because protein C has a very short half-life (6-8 hours), so it is depleted before the longer half-life procoagulant factors (II, IX, X), creating a transient prothrombotic state. Patients with pre-existing protein C or S deficiency are at highest risk. The resulting microvascular thrombosis causes skin necrosis, typically in fatty areas. Prevention involves bridging with heparin until INR is therapeutic and using lower initial Warfarin doses. Treatment: stop Warfarin, therapeutic heparin, protein C concentrate if available, and wound management.

Reference: BAD 2018; BJD Warfarin Review