A 52-year-old man with ecchymotic leg ulcers.

A 52-year-old man presented to the emergency department with a one-day history of pain and bluish discoloration of the tips of the great toes of both his feet that rapidly progressed to worsening pain, swelling, and discoloration of both feet and legs. His past medical history was significant for many years of heavy alcohol use and an episode of unprovoked venous thromboembolism two months prior to presentation. At that time, he was found to be heterozygous for Factor V Leiden mutation. After initial anticoagulation with fondaparinux, he was started on warfarin 7.5 mg daily. A removable inferior vena cava filter was placed for unclear indications. In the emergency department, his review of systems was remarkable for a one-day history of melena with hematemesis. On subsequent questioning, he admitted to only sporadic compliance with his warfarin therapy and laboratory monitoring. On physical examination, the patient was noted to have hemorrhagic bullae of the skin of the anterior pretibial surfaces of both legs (Figure 1). His laboratory data was significant for a hemoglobin of 3 g/dl (13.5-17.5 gm/ dl), white blood cell count 28,000/ mm3 (normal 4.5,000-11,000/mm3), platelet count 54,000/mm3 (normal 130,000-400,000/mm3, International Normalized Ratio (INR) > 9.5 (normal 0.9-1.1) quantitative D-dimer >5000 ng/mL(normal <200 ng/dl), and fibrinogen 311 mg/dL (normal 200-600 mg/dl). No gastrointestinal source of bleeding was identified on esophagogastroduodenoscopy. Ultrasound demonstrated bilateral popliteal thrombosis. Within hours, hemorrhagic bullae formed over both pretibial areas, and purpura began to appear on his upper extremities. He was transfused with packed red blood cells and fresh frozen plasma. Therapy for presumed warfarin-induced skin necrosis (WISN), i.e. heparin or recombinant activated protein C infusion, was withheld due to the elevated INR, thrombocytopenia, and a low hemoglobin level. Skin punch biopsy of the purpura over his legs showed separation of the stratum corneum, focal necrosis of acrosyrinx, and thrombosis of blood vessels throughout the dermis and subcutaneous tissue (Figure 2). There was no evidence of vasculitis. He ultimately developed limb gangrene, requiring bilateral above knee amputations.