ACQUIRED VON WILLEBRANDS DISEASE DUE TO ABERRANT EXPRESSION OF PLATELET GLYCOPROTEIN IB BY MARGINAL ZONE LYMPHOMA-CELLS

A 69-year-old woman presented with splenic marginal zone lymphoma asso ciated with acquired von Willebrand's disease (AVWD). Laboratory abnor malities included markedly decreased plasma levels of factor VIII coag ulant (C) activity (VIII:C 28%), von Willebrand's factor (VWF) antigen (Ag) (vWF:Ag<6%), and VWF ristocetin cofactor (RCo) activity (VWF:RCo ,<12%). VWF multimer analysis revealed a severe type II defect, Treatm ent with cryoprecipitate, high-dose gamma globulin or desmopressin giv en intravenously was unsuccessful. Clinical bleeding and coagulation a bnormalities showed transient improvement after replacement therapy wi th Humate-P concentrate. The coagulation abnormalities improved partia lly after splenectomy and completely after subsequent chemotherapy. Th e neoplastic lymphocytes in the blood and spleen strongly expressed pl atelet glycoprotein Ib (CD42) and VWF but not other platelet-associate d antigens.