BERNARD-SOULIER-LIKE FUNCTIONAL PLATELET DEFECT IN MYELODYSPLASTIC SYNDROME AND IN ACUTE MYELOBLASTIC-LEUKEMIA ASSOCIATED WITH TRILINEAGE MYELODYSPLASIA

Platelet function was studied in a child with myelodysplastic syndrome (MDS: refractory anemia with an excess of blasts) and a child with ac ute myeloblastic leukemia (AML-M6) associated with trilineage myelodys plasia (TMDS). An acquired Bernard-Soulier-like platelet defect was co nsidered in both patients with the findings of prolonged bleeding time and abnormally large platelets that failed to aggregate in response t o ristocetin. In contrast to findings in von Willebrand's disease, the abnormal response of platelets to ristocetin could not be corrected b y the addition of normal fresh plasma. The detection of abnormal plate let aggregation response to ristocetin may be a useful diagnostic find ing for clonal disorders causing impaired platelet function in MDS and coexistent TMDS associated with AML. Further studies of ristocetin-in duced platelet aggregation in a large number of these patients are req uired.