Warfarin-induced limb gangrene in the setting of lung adenocarcinoma.

A 53-year-old man with lung adenocarcinoma developed pulmonary embolism and bilateral popliteal venous thrombosis. Treated with intravenous unfractionated heparin and discharged home on warfarin, he returned a week later with extending thrombosis. Treatment with heparin followed by warfarin was reinitiated. Twenty-four hours following the re-administration of warfarin, the patient's INR increased to 14.5. The platelet count dropped by more than 50%, and he developed venous limb gangrene of the left leg and skin necrosis of the right leg. Heparin-induced thrombocytopenia was ruled out, and coagulation studies showed a severe depletion of protein C as well as increased thrombin generation. The patient was transfused with fresh frozen plasma, and vitamin K was given. Heparin was continued, and after 4 weeks, the patient improved markedly showing only minimal necrosis of the toes. Venous limb gangrene is a major complication associated with warfarin therapy. Its pathogenesis is explained by a transient hypercoagulable state produced by protein C depletion that leads to microvascular thrombi progressing to venous limb gangrene. The present case emphasizes the importance of careful anticoagulation with heparin followed by slow initiation of low-dose warfarin, in order to minimize thrombotic complications.