PO652-TUE Acquired von Willebrand syndrome (AVWS) with a type 2B phenotype secondary to an IGA autoantibody with anti-von Willebrand factor activity

ALBERTO MF; BERMEJO EI; MESCHENGIESER SS; ROMERO ML; WOODS AI; KEMPFER AC; PAIVA-PALOMINO J; PIZZOLATO MA; LAZZARI MA; SÁNCHEZ LUCEROS A

Toronto

Congreso; XXV Congress of the International Society on Thrombosis and Haemostasis and 61st Annual SSC Meeting.; 2015

International Society on Thrombosis and Haemostasis

Background: AVWS is a rare bleeding disorder and usually mimics von Willebrand disease type 1 or 2A and exceptionally 2B. Aims: To report a case of woman with AVWS with a 2B phenotype misdiagnosed as ITP. Methods: Platelet count (PC); FVIII:C; VWF:Ag; VWF:RCo; VWF multimers; VWF 2B/GP1b genotypic analysis; RIPA at 0.6 mg/mL, mixing studies with platelet rich plasma (PRP), washed platelets, poor platelet plasma (PPP), IgG depleted plasma and purified VWF. IgG, IgM and IgA anti-VWF (ELISA). Results: A 41-year-old woman with ITP under corticosteroids was referred to investigate the persistence of bleeding in spite of moderate thrombocytopenia. Laboratory showed (2010) PC 88.000/mm3, macrothrombocytopenia, FVIII 80%, VWF:Ag 50%, VWF:RCo less than 10% (VWF:RCo/VWF:Ag ratio less than 0.7), enhanced RIPA and absence of high and intermediate molecular weight multimers. Genotypic analysis was negative. The patient continued with corticosteroids and tranexamic acid was added. Compliance to treatment was irregular. On 2011, she presented gum bleeding and menorrhagia (PC 23.000/mm3), (VWF:RCo/VWF:Ag less than 0.7). She received corticosteroids plus dapsone and blood transfusion was necessary. On 2013, the patient developed diabetes. Corticosteroids were suppressed and romiplostin once a week was started. Bleedings ended when normal PC was achieved. Additional tests (mixing studies with PRP, washed platelets, PPP, IgG depleted plasma and purified VWF) allowed us to conclude that the PPP of patient contained an activity (no IgG) capable of inducing platelet agglutination of normal washed platelets in presence of purified VWF. Serum immunofixation showed a low concentration IgA-Lambda monoclonal component. Finally the presence of IgA anti-VWF was shown. Conclusion: Our findings suggest the presence of an autoantibody IgA enhancing VWF binding to platelet GP 1b resulting in type 2B-like AVWS. This case highlights the difficulties in reaching a diagnosis and in the management of bleeding in a patient with an atypical presentation of AVWS.