Polycythemia vera-associated acquired von Willebrand syndrome despite near-normal platelet count.

摘要

The pathogenesis of bleeding diathesis associated with myelo-proliferative neoplasms (MPN) Is not well understood; implicated mechanisms include acquired von Willebrand syndrome (AVWS), platelet storage pool deficiency, and defective aggregation [1]. Because MPN is also associated with abnormal clotting, antithrombotic measures including use of aspirin exacerbate the underlying bleeding diathesis. AVWS also occurs in the setting of other unrelated conditions including lymphoma, plasma cell dyscrasia, cardiovascular disease, and autoimmune disorders [2], Implicated pathoge-netic mechanisms include targeting and selective clearance of large von Willebrand factor (VWF) multimers by clonal cells, abnormal vessels/valves, and autoimmune antibodies [3,4].