Erythroid- and myeloid-lineage involvement in chronic myelomonocytic leukemia

Cell-lineage involvement in a typical case of chronic myelomonocytic leukemia (CMML) was examined by simultaneous analysis of morphology and chromosomes on the same single colonies. Cytogenetic analysis of patient's bone marrow cells showed two clones: 46,X,-Y,+M1 (63/68 cells) and 47,X,-Y,+M1,+M2 (5/68 cells). Bone marrow or peripheral blood mononuclear cells were plated at 1 x 10⁴/ml or 2 x 10⁵/ml (if thawed) in methylcellulose medium containing phytohemagglutinin-stimulated, leukocyte-conditioned medium and erythropoietin. On days 9-14 of culture, 68 single colonies were lifted and each colony served for both morphological and chromosome examination. Of the 68 colonies, 23 had two or more analyzable metaphases, yielding a total of 79 metaphases. Morphological examination revealed that 10 colonies contained macrophages (m), 10 had erythroblasts (E) and blasts (bl), and three had E, respectively. All of the single colonies were derived from abnormal clones, i.e., 22 (9m,10blE,3E) were from 46,X,-Y,+M1, and one (1m) was from 47,X,-Y,+M1,+M2. These findings demonstrate that erythroid and myeloid lineages are involved in CMML.