PRE-B ACUTE LYMPHOBLASTIC-LEUKEMIA IN A 3-YEAR-OLD BOY WITH PRE-ACUTEMYELOGENOUS LEUKEMIA MYELODYSPLASTIC SYNDROME - CYTOGENETIC EVIDENCE OF COMMON EARLY PROGENITOR-CELL ONTOGENY

Purpose: Myelodysplastic syndromes in children commonly evolve into ac ute leukemia, usually acute myelogenous leukemia (AML) and rarely acut e lymphoblastic leukemia (ALL). The lineage of the leukemia can be pre dicted based on characteristic morphologic and cytogenetic findings of the marrow and peripheral blood. Patient and Methods: A 3-year-old bo y had refractory anemia with excess blasts and abnormalities suggestiv e of pre-AML with highly unusual cytogenetic changes. ALL of pre-B phe notype developed. Results: Leukoerythroblastic anemia, pseudo Pelger-H uet neutrophils, and dysmyelopoietic hyperplasia of the marrow suggest ed likely early progression to AML. Complex cytogenetic abnormalities (monosomy 17 and 20, ring chromosome Il with deletion of bands q23, an d a derivative dicentric chromosome 12) were present in both the myelo dysplastic marrow and the subsequent AU. Conclusion: This case present s cytogenetic evidence of common early progenitor cell ontogeny of bot h malignancies (refractory anemia with excess blasts and ALL).