Essential Thrombocythemia in a Girl Associated with Acquired von Willebrand Disease

Abstract

We report an 11-year-old girl with essential thrombocythemia in association with acquired von Willebrand disease. Platelet count at presentation was 343.6 × 10⁴/μl, and she developed subcutaneous hematoma at thesite of bone marrow aspiration. Platelet aggregation studies revealed the response to collagen, epinephrine and ristocetin to be absent, and that to ADP decreased. VWF : RCo markedly decreased and the analysis of multimetric pattern of VWF showed diminished large VWF multimer. Platelet-lowering treatment with busulfan resulted in prompt disappearance of bleeding symptoms. 10 months after the start of treatment, VWF : RCo mildly rose and an increase of largeVWF multimer was observed. But, 22 months later, though platelet count fell below 40 × 10μl, large VWF multimer decreased again and low VWF : RCo persisted.