Cytogenetics in multiple myeloma and plasma cell leukemia: simultaneous cytogenetic and cytologic studies in 51 patients.

Cytogenetic studies in patients with multiple myeloma (MM) and plasma cell leukemia (PCL) have in general been largely unsuccessful. The investigation of mitoses of nonmalignant hematopoietic precursor cells, rather than mitoses of malignant plasma cells might account for the low percentage of pathological genetic findings. We investigated bone marrow (BM) cells of 51 patients both cytogenetically and cytologically. In patients with a normal karyotype (n = 39) nearly all mitoses examined cytologically (107/117) derived from granulopoietic or erythropoietic cell lineages. In contrast, 20/27 metaphases in patients with a pathological karyotype (n = 12) were found to be plasma cell mitoses. These findings may explain the low rate of chromosomal rearrangements in MM and may suggest that the real abnormality rate is considerably higher.