Diagnosis and management of acquired von Willebrand syndrome.

: The acquired von Willebrand syndrome is a rare bleeding disorder with laboratory finding similar to those of congenital von Willebrand's disease. Unlike the congenital form, however, the acquired syndrome usually occurs in persons with no personal or family history of bleeding. Large-scale studies are not available, diagnosis is still difficult, and treatment is empirical. Published findings and an international registry indicate that the syndrome is especially frequent in lympho- or myeloproliferative disorders; therefore, it should be suspected when there is excessive bleeding in patients with these disorders. Acquired von Willebrand syndrome is also associated with solid tumors, immunologic and cardiovascular, disorders. Diagnosis is based on assays measuring ristocetin cofactor activity or collagen binding; these levels are usually abnormally low, while factor VIII coagulant activity can be normal. Factor VIII/von Willebrand factor-inhibiting activities are found in only a minority of cases. Bleeding episodes in patients with the syndrome are mostly of the mucocutaneous type and can be managed with desmopressin, plasma-derived factor VIII/von Willebrand factor concentrates, and intravenous immunoglobulin. Recombinant activated factor VII, plasmapheresis, corticosteroids, and immunosuppressors combined with chemotherapy are also useful in some cases. Acquired von Willebrand syndrome, although rare, warrants further understanding for clinical practice.