NEAR-TETRAPLOID POORLY DIFFERENTIATED ACUTE MYELOID-LEUKEMIA M0 DIAGNOSED BY SHORT-TERM CULTURES WITH A PHORBOL ESTER TPA

Leukemic blasts of two patients with acute leukemia exhibited similar characteristics. They were heterogeneous in size with a diameter of 14 -30 mu m in smears and unclassifiable by morphological, cytochemical, immunophenotypic and ultrastructural examinations. Cytogenetic examina tions of both revealed a near-tetraploid karyotype. Blasts from both p atients differentiated into macrophages in cultures with 10 ng/ml 12-O -tetra-decanoylphorbol-13-acetate (TPA) which is a feature specific fo r myeloid blasts and the cases were thus classified as poorly differen tiated acute myeloid leukemias (AML MO). Near-tetraploid poorly differ entiated acute myeloid leukemias MO seem to be a special category of A ML in the morphologic, immunologic and cytogenetic (MIC) classificatio n. The presence of very large blasts in the heterogeneous blast popula tion in acute unclassified leukemias could be a morphological sign of near-tetraploid leukemias AML MO.