[Clinical and laboratory characteristics of two acute lymphoblastic leukemia patients with dicentric (9; 20) (p11 - 13; q11)].

OBJECTIVE

To explore the morphologic, immunophenotypic, cytogenetic and clinical features of acute lymphoblastic leukemia (ALL) patients with dicentric (9; 20) (p11 - 13; q11).

METHODS

Chromosome specimens of bone marrow cells were prepared by direct method and/or short-time culture. Karyo-typing was performed by R-banding technique. Dual-color fluorescence in situ hybridization (FISH) was performed using both chromosome 9 classical satellite probe and chromosome 20 alpha-satellite probe in one patient.

RESULTS

The two ALL patients were positive for CD10 and HLA-DR, showing of B cell origin. Both patients had dicentric (9; 20): case 1 was 45, XY, der (9) t (9; 20) (p11; q11), -20[20]; case 2 was 45, XX, der (9) t (9; 20) (p13; q11), t (9; 22) (q34; q11), -20[10]/46, idem, +8[16]/47, idem, +8, +21[14]. Mutual translocation between chromosomes 9 and 20 of the dicentric chromosome was confirmed by FISH in one patient.

CONCLUSIONS

Dicentric (9; 20) (p11 - 13; q11) is a rare recurring chromosome abnormality associated with ALL. Because of the subtle nature of the translocation, FISH is essential for the detection of this abnormality.