Dicentric(7;9)(p11;p11) in Acute Lymphoblastic Leukemia: A Clinical and Laboratory Study of 7 Cases.

The clinical and experimental features of 7 cases of acute lymphoblastic leukemia(ALL) with the dicentric chromosome dic(7;9) (p11;p11) were investigated. Five patients were male and two were female. Their median age was 32 years. Cytogenetic examination of bone marrow cells was performed by direct method or 24h culture method. R banding techique was used for karyotype analysis. Among them, dic(7;9) was found to be the sole abnormality in 2 cases, t(9;22) and other additional aberrations were detected besides dic(7;9) in 4 cases as well as dic(7;9) and other abnormalities without t(9;22) were found in one case. Hyperleukocytosis(>100×10⁹/L) was found in 4 cases with dic(7;9) and t(9;22), whereas 3 cases with sole dic(7;9) or dic(7;9) and other abnormalities had a WBC of 1.0–100×10⁹/L. Enlargement of liver, spleen and/or lymph nodes were found in 6 cases. Immunophenotyping analysis showed that 5/6 cases of dic(7;9) ALL were B lineage ALL. Dual-color FISH detected BCR/ABL rearrangment 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 patinting technique using whole chromosome paint probes for both chromosomes 7 and 9. This study has increased the number of reported cases of dic(7;9) from 8 to 15. Thus, we consider that dic(7;9) was a rare, but recurrent chromosome abnormality in ALL. It may appear as a primary change but also as secondary one following t(9;22), and had unique clinical and laboratory features.