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

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.