CYTOGENETIC PROFILE OF MINIMALLY DIFFERENTIATED (FAB M0) ACUTE MYELOID-LEUKEMIA - CORRELATION WITH CLINICOBIOLOGIC FINDINGS

Cytogenetic data were studied in 26 patients with de novo acute myeloi d leukemia (AML) with minimal myeloid differentiation, corresponding t o the M0 subtype of the French-American-British classification, in cor relation with cytoimmunologic and clinical findings. Clonal abnormalit ies were detected in 21 cases (80.7%), 12 of which had a complex karyo type. Partial or total monosomy 5q and/or 7q was found, either as the sole aberration or in all abnormal metaphases, in 11 patients; in 8 ca ses, additional chromosome changes were present, including rearrangeme nts involving 12p12-13 and 2p12-15 seen in 3 cases each. Five patients had trisomy 13 as a possible primary chromosome change; in 5 cases, n onrecurrent chromsome abnormalities were observed. Comparison of these findings with chromosome data from 42 patients with AML-M1 shows that abnormal karyotypes, complex karyotypes, unbalanced chromosome change s (-5/5q- and/or -7/7q- and +13) were observed much more frequently in AML-M0 than in AML-M1. Patients with abnormalities of chromosome 5 an d/or 7 frequently showed trilineage myelodysplasia and low white blood cell count. Despite their relatively young age, complete remission wa s achieved in 4 of 11 patients only. Patients with +13 were elderly ma les with frequent professional exposure to myelotoxic agents. Unlike p atients with clonal abnormalities, most AML-M0 patients with normal ka ryotype showed 1% to 2% peroxidase-positive blast cells at light micro scopy and frequently achieved CR. It is concluded that (1) AML-M0 show s a distinct cytogenetic profile, partially recalling that of therapy- related AML, (2) different cytogenetic groups of AML-M0 can be ideniti fied showing characteristic clinicobiologic features, and (3) chromoso me rearrangements may partially account for the unfavorable outcome fr equently observed in these patients. (C) 1995 by The American Society of Hematology.