Increased activity of factor VIII coagulant associated with venous ulcer in a patient with Klinefelter's syndrome.

Klinefelter's syndrome is the most frequent major abnormality of sexual differentiation in men with two or more X chromosomes. Recurrent venous ulcers as a result of a post-thrombotic syndrome are a well known symptom in patients with Klinefelter's syndrome. Until now the underlying pathomechanisms are not completely understood. Platelet hyperaggregability, factor V Leiden mutation and abnormalities in fibrinolysis were implicated as possible contributing factors. Here we describe the detection of an increased activity of factor VIII coagulant (factor VIII:C). This is the first case report on increased factor VIII:C activity associated with venous ulcers in a patient with Klinefelter's syndrome. Elevated factor VIII plasma levels are gradually accepted to be associated with an increased risk for venous thromboembolism. Therefore, we discuss that the examination of factor VIII:C may help in clarifying individual thromboembolic risks, especially in patients with Klinefelter's syndrome.