Heparin skin necrosis: delayed occurrence in a patient on hemodialysis. A case of skin necrosis in a patient receiving intravenous (IV) heparin during routine intermittent hemodialysis is reported. Multiple erythematous, tender lesions developed over the abdomen and thighs and rapidly became necrotic. Biopsies showed fibrin thrombi in the dermal venules and capillaries, but no cellular infiltrate. The patient was in her third month of regular hemodialysis. Skin necrosis associated with the use of heparin usually occurs within 2 weeks of beginning heparin therapy and has not been reported in patients receiving heparin with hemodialysis. Possible mechanisms, including acquired antithrombin III deficiency leading to heparin-induced skin necrosis, are discussed. 