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.