[Significance of the chromosomal findings in acute myeloid leukemia with maturation (M2)].

Chromosomal banding studies were performed on 13 patients with acute myeloid leukemia with maturation (M 2). Six patients revealed t (8;21) (q22;q22), five normal karyotype, and the remaining two +8 and inv (16) (p13 q22), respectively. Apparent pseudo-Pelger-Huët anomalies in mature neutrophils were observed in all the 6 patients with t (8;21), but in only one of the 5 patients with normal karyotype. Neutrophil alkaline phosphatase (NAP) score decreased in all but one in the former group while it increased in all the patients in the latter group. The former group had a median follow-up of 20.8 months or more, whereas the latter group had a median survival of 4.4 months or more. Accordingly, it was suggested that two major chromosome subgroups may be present among patients diagnosed as having M 2: one subgroup with t (8;21) and the other with normal karyotype. One patient with M 2 and inv (16) showed almost the same hematologic features as those observed in patients with acute myelomonocytic leukemia (M 4) and inv (16) except for a small population (6.8%) of monocytoid cells in the bone marrow.