A family having type 2B von Willebrand disease with a novel VWF p.R1308S mutation: Detection of characteristic platelet aggregates on peripheral blood smears as the key aspect of diagnosis.

Type 2B von Willebrand disease (VWD) is frequently associated with distinct platelet morphology. Here we present a familial case of type 2B VWD with a novel VWF mutation (p.R1308S), which caused neonatal thrombocytopenia. The mother had been treated for refractory immune thrombocytopenia (ITP) for more than 20years. The most important hematological features of this case were large platelets and platelet aggregates detected on peripheral blood smears. Hemostatic tests showed enhanced ristocetin-induced platelet agglutination at low-ristocetin concentrations, absence of high-molecular weight von Willebrand factor (VWF) multimers, and low VWF cofactor activity/antigen ratio. In patients with intractable ITP, family history of ITP and consecutive neonatal thrombocytopenia, the differential diagnosis of congenital thrombocytopenia is mandatory. For this purpose, the identification of large platelets and platelet aggregates on peripheral blood smears is the key aspect of type 2B VWD diagnosis.