OBJECTIVETo investigate the laboratory and clinical features of 7 cases of acute lymphoblastic leukemia (ALL) with dic(7;9) (pll;pll).

METHODSCytogenetic examination of bone marrow cells was performed by direct method or short-term culture method. R banding technique was used for karyotype analysis. bcr/abl fusion gene was detected by interphase FISH using dual-color bcr/abl probe in 6 cases. FISH using chromosome 7-specific alpha-satellite DNA probe and chromosome 9-specific alpha-satellite DNA probe and chromosome painting using whole chromosome 7 and 9 paints probes were performed respectively.

RESULTSSeven (0.88%) of 800 ALL patients were found to have dic(7;9) abnormality. Among them, dic(7;9) was the sole abnormality in 2 cases, t(9;22), other additional aberrations besides dic(7;9) in 4 cases and dic (7;9) with other abnormalities but no t(9;22) in one case. Hyperleukocytosis (> 100 x 10(9)/L) was found in 4 cases with dic(7;9) and t(9;22), and patients without t(9;22) had WBC < 100 x 10(9)/L. Enlargement of liver, spleen and/or lymph nodes were found in 6 cases. Immunophenotyping showed that 5/6 cases of dic (7;9) ALL were of B lineage. Dual-color FISH detected bcr/abl rearrangement in 3/6 cases and confirmed that the centromere of the derivative chromosome was originated from both chromosomes 7 and 9. A reciprocal translocation between chromosomes 7 and 9 was proved by chromosome painting.

CONCLUSIONdic(7;9) was a rare, but recurrent chromosome abnormality in ALL and had some clinical and laboratory features.