Chromosome studies in acute leukemias developing in patients with multiple myeloma.

Chromosomal findings are reported in three patients with acute myelomonocytic leukemia and in one with reticulosarcoma leukemia who had been treated for multiple myeloma with melphalan and X-ray. All four patients had striking chromosomal anomalies. An iatrogenic causation of aneuploidy is suggested. This is supported by chromosomal findings in patients with acute leukemia following polycythemia vera and Hodgkin's disease; practically all of the leukemias have been aneuploid. A comparison is made of such "secondary" acute leukemias with "primary" acute leukemias that are aneuploid in only 40% of the cases. Chromosomal changes are not considered to be the initial event in leukemogenesis.