The acquired von Willebrand syndrome (AVWS) is a rare
bleeding disorder with laboratory findings similar to those for congenital
von Willebrand disease. Unlike the congenital form, AVWS usually occurs in individuals with no personal or family history of
bleeding. Large studies on AVWS are not available, diagnosis remains difficult and treatment empirical. Acquired von Willebrand syndrome is especially frequent in lympho- or
myeloproliferative disorders. It is associated with solid tumours, immunological and cardiovascular disorders as well as other miscellaneous conditions. Diagnosis of AVWS is based on assays measuring
ristocetin cofactor activity or
collagen binding, which are usually abnormally low, while
factor VIII coagulant activity is some-times within the reference range. FVIII/VWF inhibiting activities are found in only a minority of cases.
Bleeding episodes in patients with AVWS are mostly of the mucocutaneous type and can be managed with
desmopressin, plasma-derived
factor VIII/von Willebrand factor (FVIII/VWF) concentrates and
intravenous immunoglobulin. Recombinant
activated factor VII can be useful in cases unresponsive to standard
therapy. In conclusion, the AVWS, although rare, is certainly underestimated in clinical practice: The actual clinical impact of AVWS should be evaluated by prospective studies. The authors are co-ordinating an updated version of the International Registry on AVWS that will allow data to be entered directly online.