Diagnostic Workup of Patients with Acquired Von Willebrand’s Syndrome.

Acquired von Willebrand’s syndrome (AVWS) is a rare but probably underdiagnosed hemorrhagic disorder often associated with hematological or cardiovalvular disorders. Diagnostic workup remains challenging, particularly in patients with normal or increased von Willebrand factor antigen (Ag) and ristocetin cofactor (RCo). Here, we present a retrospective single-center study of 35 patients diagnosed with AVWS based on (i) a history of recent onset of bleeding, (ii) a negative family history of von Willebrand’s disease, and (iii) abnormal plasma VWF multimers. AVWS was associated with monoclonal gammopathy (n=11), cardiovalvular disorders (n=16), or other conditions (n=8) including myeloproliferative and autoimmune disorders. The PFA-100^® screening test was inconclusive due to anemia (hematocrit <30 %) or thrombocytopenia (<100/nl) in 10 patients (29 %); prolonged closure times were observed using collagen/epinephrine and collagen/adrenalin in 20 of 25 (80 %) and 18 of 25 (72 %) patients, respectively. Factor VIII:C was reduced below 50 IU/dl in 7 of 35 patients (20 %). VWF Ag and RCo were reduced below 50 IU/dl in 8 patients (23 %). VWF Ag and RCo were normal or increased in all patients with cardiovalvular disease and in four of eleven patients with gammopathy. Median VWF Ag was higher in cardiovalvular disease (median 202 IU/dl, range 90 to 608) compared to gammopathy (median 31 IU/dl, range 8 to 468, p<0.02 by Mann Whitney U test). Of 27 patients with normal or increased VWF Ag and RCo, 12 (44 %) had a reduced collagen binding activity (CBA) or CBA to Ag ratio <0.7; 10 (37 %) had a borderline CBA ratio between 0.7 and 0.8; 5 (19 %) had a normal CBA >0.8. A normal or increased VWF Ag together with a CBA ratio >0.7 was observed both in patients with cardiovalvular disease (n=9), gammopathy (n=2) and other disorders (n=4). However, in all patients the largest VWF multimers were decreased (n=14) or absent (n=21). In conclusion, no single test was sufficient to detect all cases of AVWS. The PFA-100^® test is of limited use in this population because of its limitation in anemia or thrombocytopenia and because of its low sensitivity. A significant number of patients present with a normal or increased VWF Ag and RCo as well as a CBA ratio >0.7 emphasizing the importance of multimer analysis in all patients with suspected AVWS.