TETRAPLOID OR NEAR-TETRAPLOID CLONES CHARACTERIZED BY 2 8-21-TRANSLOCATIONS AND OTHER CHROMOSOMAL-ABNORMALITIES IN 2 PATIENTS WITH ACUTE MYELOBLASTIC-LEUKEMIA

Acute myeloblastic leukemia (AML) with tetraploidy is rare. There have been only six such cases studied with banding techniques in the liter ature. Two rr ere diagnosed as having AML-M2 and found to have similar near-tetraploid karyotypes with t(8;21) and missing Y chromosomes. We report two further cases of AML with tetraploid or near-tetraploid cl ones characterized by two t(8;21) and other chromosomal changes. Their cytogenetic findings were compatible with the diagnosis of AML-M2. Gi ant and bizarre blasts rt ere seen on bone marrow (BM) smears from bot h cases. Immunologically, the blasts express CD2, CD15, and HLA-DR in case 3 and CD2 and CD65 in case 2. Cytogenetic studies on BM cells at diagnosis revealed that both cases had three related abnormal clones b esides a normal one: 46,XY, t(8;21) (2%)/46,idem,add(7)(q31)(6.8%)/92, idemx2 (80.6%) for case 1; and ll,XX,t(8;21) (13.4%)/47,idem,+4 (46.3 %)/94, idemx2 (39.1%) for case 2. Flow cytometric analysis displayed t wo cell populations in the former: one rr as in the diploid range and the other was in the tetraploid range. The patients did not obtain com plete remissions and survived four and six months, respectively. These results indicate that tetraploid or near-tetraploid clones are second ary events which are associated with t(8;21) leukemia and may be assoc iated with poor prognostic significance. (C) Elsevier Science Inc., 19 96