Acquired von Willebrand's disease.

avWD is a rare entity that is primarily associated with lymphoproliferative disorders, most commonly with multiple myeloma, lymphoma, and the myeloproliferative diseases. Various pathogenetic mechanisms have been postulated. The most commonly seen is antibodies directed against the FVIII complex, resulting in either its accelerated destruction or its accelerated clearance by the reticuloendothelial system. There may be immunoadsorption of the FVIII complexes onto the clones of malignant cells, as has been reported in several cases, or proteolysis may be causing the peripheral destruction of the FVIII complex. Lastly, as seen in hypothyroidism, global decrease in production of the multimers also results in avWD. The treatment, in general, should be aimed at controlling the underlying disorder and at stopping any life-threatening hemorrhage. The treatment includes any or all of the following: DDAVP, cryoprecipitate, FVIII concentrates, extracorporeal immunoadsorption, and chemotherapy as needed to control the underlying disorders. The screening tests that will allow for the detection of the avWD include measurement of the bleeding time, the FVIII:C, FVIII:vWF, and the FVIII:RCoF. FVIII:C inhibitors can be demonstrated by mixing the patient plasma with normal plasma. A normal prothrombin time (PT), activated partial thromboplastin time (APTT), and thrombin time (TT) are expected. Clinically, these patients present with mucosal bleeding, and in avWD tend to have an association with lymphoproliferative malignancies. They tend to be elderly patients with no prior history of bleeding diathesis and to have negative family histories for coagulopathies. Further study of these patients is warranted, because this disorder appears to have a multifactorial etiology. Increasing our understanding of avWD may increase our understanding of congenital vWD, thus allowing us to more effectively treat all patients with von Willebrand's disease.