Acquired von willebrand syndrome in patients with philadelphia-negative myeloproliferative neoplasm.

Background: Acquired von Willebrand syndrome (AVWS) has not been investigated in Korean patients with Philadelphia chromosome-negative myeloproliferative neoplasm. Methods: This study analyzed the prevalence at diagnosis and clinical features of AVWS in patients with essential thrombocythemia (ET), polycythemia vera (PV), prefibrotic/early primary myelofibrosis (pre-PMF), or overt PMF (PMF) diagnosed between January 2019 and December 2021 at Chungam National University Hospital, Daejeon, Korea. AVWS was defined as below the lower reference limit (56%) of ristocetin cofactor activity (VWF:RCo). Results: Sixty-four consecutive patients (36 with ET, 17 with PV, 6 with pre-PMF, and 5 with PMF; 30 men and 34 women) with a median age of 67 years (range, 18‒87 yr) were followed for a median of 25.1 months (range, 2.6‒46.4 mo). AVWS was detected in 20 (31.3%) patients at diagnosis and was most frequent in ET patients (41.4%), followed by patients with pre-PMF (33.3%) and PV (17.6%) patients. VWF:RCo was negatively correlated with the platelet count (r=0.937; Conclusion: AVWS based on VWF:RCo was common in patients with ET and pre-PMF, but less common in patients with PV in the Korean population. Clinically significant bleeding is rare in these patients.