Cutaneous drug reactions to anticoagulants

Warfarin-induced skin necrosis is caused by a Nonimmune-mediated transient hypercoagulable state at the initiation of therapy. Grossly and histopathologically it is very hard to differentiate from heparin-induced skin necrosis (HISN). HISN is a manifestation of heparin-induced thrombocytopenia and thrombosis syndrome (HITT); it is a type II Antibody-Mediated hypersensitivity reaction. It is clinically important because the rapidly progressive cutaneous necrosis heralds a Life-Threatening systemic reaction to heparin. Delayed-Type hypersensitivity to heparin is a far more common cutaneous reaction to heparin and can look quite similar to HISN at the outset. It is critical to differentiate between the two because of the clinical management implications.