DYSPLASIA OF BONE-MARROW MEGAKARYOCYTES IN ACUTE MYELODISPLASTIC LEUKEMIA - MORPHOLOGICAL, CYTOCHEMICAL AND CYTOGENETIC DATA

Bone marrow megakaryocyte patterns and blood platelet counts in 87 AML patients have been studied. The megakaryocyte number was increased in 16.1% of cases, while in 17.2% of cases it was normal. These indices were sharply decreased in remaining patients. In fourteen cases no meg akaryocytes were detected. Dysplasia of megakaryocytes was revealed in nearly a half of the cases investigated. As a rule, megakaryocyte pro duction was ineffective: 93% of patients had thrombocytopenia. Increas ed megakaryocyte numbers were comparatively common and associated with MO and M4 FAB variants. Megakaryocytosis was observed in each of the five patients with 3q21 and/or 3q26 abnormalities and was significantl y less common in the cases with other karyotype changes. The frequency of the (8; 21)(q22; q22) translocation was significantly lower in pat ients with dysplasia of megakaryocytes than without it. Increased mega karyocyte numbers did not correlate with a dysplastic pattern of granu locytic and erythroid precursors in bone marrow. Marked megakaryocytos is and high blood platelet level (more than 400 x 10(9)/L) were reveal ed in four of 87 patients. In two of them abnormalities of both 3q21 a nd 3q26 were found, one patient had monosomy 7 only and in one case no rmal karyotype was detected. Possible mechanisms of megakaryocytic dys plasia in AML are discussed.