Philadelphia-negative myeloproliferative neoplasms and acquired von Willebrand syndrome: only pertinent at diagnosis?

Background: Philadelphia-negative myeloproliferative neoplasms (MPNs) are associated with both thrombotic and bleeding complications. Acquired von Willebrand syndrome (AVWS) is particularly reported in essential thrombocythemia (ET), and its role in bleeding risk remains uncertain. Objectives: This study characterized patients with AVWS at the time of MPN diagnosis and evaluated the association with clinical events. Methods: In our single-center cohort study, 178 patients diagnosed with polycythemia vera (PV), ET, or prefibrotic myelofibrosis (pre-PMF) were included. AVWS was assessed at diagnosis and was defined by a von Willebrand factor:glycoprotein IbM/von Willebrand factor:Ag ratio of <0.65. Results: Prevalence of AVWS was 38% in the whole cohort (46.3% in PV, 33% in ET, and 36.4% in pre-PMF cases). Patients with AVWS showed a more proliferative profile with elevated platelets, leukocytes, hematocrit, and lactate dehydrogenase levels. The incidence of AVWS increased with the number of elevated blood cell counts, particularly in patients with 3 myeloid lineages implications (OR, 6.14; 95% CI, 2.22-18.9; Conclusion: AVWS affects over one-third of newly diagnosed patients with MPN, particularly women or those with thrombocytosis or polycythemia. These results suggest AVWS is not solely driven by extreme thrombocytosis but also by overall myeloproliferative burden.