[Durable remission attained with rituximab therapy in a patient with acquired von Willebrand syndrome associated with CD20-positive lymphoproliferative disorder].

A 61-year-old female with no history of bleeding was admitted to our hospital owing to persistent bleeding after the left knee joint injection and activated partial thromboplastin time prolongation. Subsequent coagulation tests revealed a critically declined level of the von Willebrand factor (VWF) antigen (<10%) and activity (<10%) measurement besides a significantly declined factor VIII activity (4%). Despite diagnosing her with acquired von Willebrand syndrome (AvWS) and managing her bleeding with desmopressin acetate hydrate (DDAVP), we could not precisely make a definitive diagnosis the underlying disorder. More than 15 months after the onset of AvWS, CD20-positive atypical lymphocytes appeared in the peripheral blood and bone marrow without systemic lymphadenopathy. We initiated rituximab monotherapy eight times a week for CD20-positive lymphoproliferative disorders. The treatment not only caused the disappearance of the clonal expansion of CD20-positive atypical lymphocytes in both peripheral blood and bone marrow but also exhibited the clinical remission of AvWS. In addition, the maintenance therapy with rituximab every 3 months resulted in the durable remission of over 5 years. AvWS is a rare bleeding disorder, similar to von Willebrand disease, which arises from various underlying diseases. Our experience with this case highlights that rituximab proved to be one of the effective and well-tolerated treatment options for AvWS associated with CD20-positive B-cell lymphoproliferative disorders.