8;21 translocation in acute nonlymphocytic leukemia. Occurrence in M1 and M2 FAB subtypes.

Ten patients with acute nonlymphocytic leukemia (ANLL) and the 8;21 chromosome translocation were observed over an eight-year period. The mean age of the patients was 31, and nine achieved a complete remission. Six were classified as ANLL-M2, three as ANLL-M1, and one as borderline M1/M2. A missing sex chromosome was also observed in four of the ANLL-M2 patients but not in the three M1 patients. An increased number of dyspoietic myeloid cells and/or basophils was present in four patients in day 14 or 21 marrows after induction therapy, but this feature did not appear to adversely affect prognosis. Previous reports have stated that t(8;21) occurs almost exclusively in ANLL-M2. However, by revised French-American-British criteria for classification of ANLL, the M1 subtype may also be observed with significant frequency.