Thrombocytapheresis as a Bridge Intervention in JAK2 ‐Mutant Myeloproliferative Neoplasm Complicated by Acquired von Willebrand Disease: A Case Report

ABSTRACT

Acquired von Willebrand disease (AvWD) in myeloproliferative neoplasms with extreme thrombocytosis causes paradoxical bleeding due to the mechanism of adsorption and ADAMTS13‐mediated proteolysis of high‐molecular‐weight von Willebrand factor (vWF) multimers. When first‐line cytoreductive therapy fails due to intolerance or nonadherence, rapid alternatives are limited. We describe a 74‐year‐old woman with JAK2V617F‐mutated myeloproliferative neoplasm and hydroxyurea intolerance who presented with active mucosal bleeding and a platelet count of 952 000/μL. vWF antigen (vWF:Ag) was 0.37 IU/mL (reference range: 0.50–2.00 IU/mL), and vWF Ristocetin Cofactor activity (vWF:RCo) was 0.21 IU/mL (activity/antigen ratio 0.57; reference range 0.7–1.3), consistent with AvWD. A single thrombocytapheresis session on the Fresenius COM.TEC platform reduced the platelet count to 277 000/μL, with prompt cessation of bleeding. Repeat testing at 24 h showed improvement in vWF:RCo to 0.48 IU/mL (ratio 0.68), which likely reflects restoration of functional high‐molecular‐weight multimers. In this single case, thrombocytapheresis provided rapid and effective platelet reduction for AvWD secondary to myeloproliferative neoplasms when pharmacological cytoreduction is inadequate.