CD7(+) near-tetraploid acute myeloblastic leukemia M2 with double t(8;21)(q22;q22) translocations and AML1/ETO rearrangements detected by fluorescence in situ hybridization analysis

Near-tetraploidy is a rare cytogenetic abnormality observed in acute myelob lastic leukemia (AML). It was recently suggested that near-tetraploid AML m ay be associated specifically with t(8;21)(q22;q22). We report here a new c ase of near-tetraploid AML with double t(8;21)(q22;q22) translocations. A 6 1-year-old woman was admitted to our hospital because of high fever and pan cytopenia. Her bone marrow was markedly hypercellular, with 72% giant and b izarre myeloblasts. These myeloblasts were positive for CD7. CD13, CD19, CD 33, CD34, and HLA-DR but negative for CD2 and CD56. The patient's disease w as diagnosed as the M2 subtype of AML (by French-American-British classific ation). Chromosome analysis revealed a karyotype of 45,X -X, t(8;21) (q22;q 22)[1]/90,XXX,-X,t(8;21)(q22;q22)x2,-9[7]/46,XX[12]. Fluorescence in situ h ybridization (FISH) analysis with an AML1/ETO probe detected 4 fusion signa ls on 2 der(8)t(8:21) and 2 der(21)t(8;21) in near-tetraploid cells. Revers e transcription-polymerase chain reaction analysis revealed the presence of the AML1/ETO fusion transcript. These findings suggested that near-tetrapl oidy may be a secondary genetic change originating from a diploid clone wit h t(8;21) and that 2 AML1/ETO fusion genes are generated on the der(8)t(8;2 1) in near-tetraploid clones. Consideration of the other reported cases sug gests that the immunophenotypes of near-tetraploid AML with double t(8,21) are heterogenous. but it is possible that t(8;21)-AML with expression of CD 2 or CD7 may be associated with a secondary clonal evolution to near-tetrap loidy. (C) 2001 The Japanese Society of Hematology.