3 CASES OF NEAR-TETRAPLOID ACUTE MYELOID LEUKEMIAS ORIGINATING IN PLURIPOTENT MYELOID PROGENITORS

We report three cases of acute myeloid leukemia (AML) with a near-tetr aploid karyotype in most metaphases while lacking chromosomal abnormal ities typical for AML. All patients, 63, 72 and 81 years old, were fem ale. In two cases, AML was diagnosed 5-7 months after a cytopenic peri od while the third patient had a secondary AML after therapy for a ple ural tumor. Leukemic blasts were classified as AML MO, AML M1 and AML without further specification. Two patients died on the 18th and 52nd day after the start of cytotoxic chemotherapy, the third patient refus ed chemotherapy and died 22 days after the diagnosis. The three patien ts may represent a distinct AML category with the following features: (1) the near-tetraploid karyotype in most bone marrow metaphases exami ned at diagnosis of AML; (2) the presence of very large myeloid blasts in the bone marrow and dysplastic changes in erythroid and/or megakar yocytic lineages pointing to the origin of AML in pluripotent myeloid progenitor cells; (3) the expression of the CD34 antigen; (4) the low growth of granulocyte-macrophage colony forming cells in culture; and (5) the presence of a preleukemic phase, a higher age and a poor progn osis. (C) 1998 Elsevier Science Ltd. All rights reserved.