von Willebrand's disease characterized by increased ristocetin sensitivity and the presence of all von Willebrand factor multimers in plasma: a new subtype.

The clinical and laboratory features of a patient with a recently recognized new variant of von Willebrand's disease are presented. The importance of this variant is that it is associated with a clinically significant bleeding diathesis but with a normal skin bleeding time, PTTK, factor VIIIc and platelet aggregation with 1 mg/ml ristocetin. The distinctive laboratory features are increased platelet sensitivity to low concentrations of ristocetin, and the presence of all plasma von Willebrand factor multimers, but in reduced amounts. The need for thorough investigation of patients with significant bleeding history despite apparently normal screening tests is emphasized.