Type 2B and pseudo type 2B Von Willebrand disease; A report of three cases

Increased affinity of Von Willebrand factor (VWF) for its platelet receptor GPIb-GPIX complex is responsible of an hemorrhagic disease, which is the Von Willebrand disease (VWD) type 2B when the molecular abnormality is located on the VWF, and the platelet-type 2B VWD when the mutation concern the platelet receptor. Haemostatic abnormalities in these bleeding disorders are similar; prolonged bleeding time, fluctuating thrombocytopenia, decreased factor VIII-VWF complex, and an increased response to low dose of ristocetin in platelets rich plasma. High molecular weight VWF multimers are decreased. We report here 2 cases of type 2B VWD and 1 case of platelet type 2B VWD. The distinction between these 2 diseases was established by studying platelet aggregation with weak doses of ristocetin in mixtures of washed platelets (of normal control or patient) + poor platelets plasma (normal or patient). In one case, VWD 2B was discovered late in a 49 years old man, and the factor VIIIC-VWF complex was not diminished. The distinction between these two congenital diseases is important for the treatment of bleeding manifestations which need VWF concentrates infusions in type 2B VWD and administration of platelets concentrates in pseudo type 2B VWD. © 2005 Elsevier SAS. Tous droits réservés.