Acquired von Willebrand Syndrome: A Comprehensive Review and a Nordic Perspective.

Acquired von Willebrand syndrome (AVWS) is a rare condition characterized by an acquired functional and/or absolute deficiency of the von Willebrand factor (VWF) protein. The absence of widely accepted diagnostic criteria has hampered accurate estimates of incidence and prevalence, which are largely currently unknown. As bleeding symptoms are not included in the most widely used definitions, AVWS should be managed as a risk factor for bleeding, rather than a specific disease entity. The diagnostic workup is cumbersome, involving measurement of both VWF antigen, VWF glycoprotein Ib binding activity, VWF collagen binding activity, and, preferentially, also VWF multimer analyses. Moreover, since the presence of bleeding symptoms is not required for diagnosis, the condition is probably underdiagnosed. In contrast to acquired hemophilia, AVWS is seldom caused by the presence of specific antibodies, but rather secondary to another disorder, most commonly lymphoproliferative, myeloproliferative, cardiovascular, and autoimmune disorders. Pathogenesis of AVWS varies according to the underlying disorder and includes nonspecific adsorption of VWF to antibodies, adsorption onto surfaces of neoplastic cells, mechanical injury, or VWF proteolysis. Treatment includes treating the underlying cause as well as stopping acute bleeds. Here, we present a comprehensive review of what is currently known regarding demographics, diagnostics, and clinical presentation of the syndrome. Since no prospective treatment studies have been performed, treatment choices must be based on data from registries and case reports that are also summarized. Moreover, we present treatment experiences of previously unpublished Nordic cases.