Acquired Factor V Deficiency: A New Cause of Bleeding in Patients with Chronic Myeloid Leukemia and Extreme Leukocytosis?

Bleeding complications in patients with MPNs are known to be related to acquired von Willebrand disease or platelet dysfunction. Here, we describe two very similar cases of chronic-phase CML with extreme leukocytosis (>500,000/mcL) and deep tissue bleeding after a minor trauma, who had increased PT and PTT, normal VWF antigen and activity. The patients were found to have acquired factor V deficiency. Factor V deficiency as a cause of bleeding in patients with uncontrolled CML has not yet been reported. Bleeding resolved after correction of hyperleukocytosis and FV level improved. We conclude that acquired FV deficiency is possible in patients with uncontrolled CML and extreme leukocytosis.