The paradox of bleeding and thrombosis in thrombocythemia: is von Willebrand factor the link?

Thrombosis and bleeding, reflecting the extreme ends of hemostasis, are common complications in patients with thrombocythemia in its primary form or in association with polycythemia vera. The pathogenesis of these thrombohemorrhagic predispositions is not clearly understood. In the present study we describe the paradoxical and sequential occurrence of thrombotic and bleeding complications in six patients with thrombocythemia. Strikingly, in all patients some abnormality of plasma von Willebrand factor was detected. The potential role of von Willebrand factor in the pathogenesis of these hemostatic complications is discussed.