A Rare Case of Acquired Von Willebrand Syndrome Type 2B: Diagnosis, Treatment, and Underlying Pathophysiology

Background: Acquired von Willebrand syndrome (AVWS) is a rare bleeding disorder that usually mimics type 1 or 2A von Willebrand disease (VWD). Key Clinical Question: Can AVWS mimic the phenotype of type 2B VWD? Clinical Approach: A 64-year-old male patient presented with thrombocytopenia, normal routine hemostasis results, and normal VWF antigen and factor VIII levels but reduced von Willebrand factor (VWF) activity (31 IU/dL). The ristocetin-induced platelet aggregation test showed paradoxical aggregation at low doses of ristocetin, suggesting type 2B VWD, but no deleterious sequence variation was found in either the VWF or GP1BA genes, compatible with AVWS. Serum protein electrophoresis revealed a monoclonal immunoglobulin G antibody. Conclusion: This AVWS with a 2B phenotype VWD was probably related to a monoclonal immunoglobulin G antibody causing a VWF conformational change, resulting in increased affinity to platelet glycoprotein-Ib. In the event of surgery or bleeding, treatment with vonicog alfa seems to be the best option for this patient.