Double minutes in acute myeloid leukemia.

Five out of 110 patients with acute myeloid leukemia (AML) showed double minutes (DM) in cytogenetic preparations. DM were found to occur predominantly in elderly patients, and in erythroleukemia or acute myelomonocytic leukemia. The five patients were apparently divided into two groups according to the number of DM per cell. Patients with few sets of DM had exclusively complex karyotypes and a poor prognosis while patients with numerous DM had otherwise normal or nearly normal karyotypes and a good prognosis. Data on 11 previously reported cases of AML with DM were collected from the literature and consistent results were revealed except that several of the 11 patients were diagnosed as having acute myeloblastic leukemia (M1 and M2 in the FAB classification), which is apparently due to differences in diagnostic criteria. Therefore, numerous or few DM in a cell might relate to different entities. When the number of DM was small they might have resulted from breakdown of existing chromosomes.