Petechiae, Ecchymoses, and Necrosis of Skin Induced by Coumarin Congeners

A rare complication of coumarin-congener anticoagulant therapy characterized by a sequence of skin lesions (petechiae, ecchymoses, and hemorrhagic infarcts) in random sites is well documented in the foreign literature and, as far as we know, is almost unknown in the American literature. These skin lesions are manifest between the third and the tenth day of anticoagulant therapy, 90% occurring within the third to the sixth day. These alarming lesions are associated only with the use of coumarin congeners, bishydroxycoumarin (Dicoumarol) being involved most frequently. Sodium heparin has never been implicated. A pathogenesis is proposed which nicely accommodates the morphologic features of this dermatopathy. However, unresolved, enigmatic clinical aspects remain.