[Skin necrosis: a paradoxical complication of anticoagulation].

Skin necrosis is an uncommon complication associated with coumarin or heparin therapy. The gross appearance and histology of the lesions--a paradoxical thrombosis of skin vessels--are identical. However, skin necrosis is the symptom of two different disorders. Coumarin necrosis may be related to reduced levels of protein C or S during the early stages of anticoagulation. It is possible to continue the warfarin therapy, simultaneously with heparin, if further anticoagulation is still required. In contrast, heparin necrosis is a manifestation of the potentially fatal heparin-associated thrombocytopenia and thrombosis syndrome (HATT). Immediate discontinuation of heparin is mandatory.