Warfarin skin necrosis. The role of factor VII

Necrosis of cutaneous and subcutaneous tissue is a rare complication of therapy of with oral anticoagulants, and is related to the use of loading-dose regimes. Three cases are reported, and demonstrate that the principal histopathological feature is thrombosis within the subcutaneous vasculature. The effect of large doses of anticoagulant on the levels of the vitamin K dependent clotting factors provides a satisfactory model for the temporal sequence of events in this syndrome. The occurrence of intravascular thrombosis with low or absent levels of Factor VII indicates that the intrinsic clotting system is of primary importance in venous thrombosis. This complication of anticoagulant therapy is not seen if loading-dose regimes are avoided.