OBJECTIVETo explore the morphology, immunophenotype, cytogenetics and clinical features of TCF3-PBX1 fusion gene positive adult acute lymphoblastic leukemia (ALL).

METHODSR banding was used to analyze conventional cytogenetics (CC), interphase fluorescence in situ hybridization (iFISH) and RT-PCR to detect the TCF3-PBX1 fusion gene, and flow cytometry to immunophenotype. The clinical and laboratory features and long-term follow-up of the patients were analyzed.

RESULTSThe incidence of 19 TCF3-PBX1-positive adult ALL was 3.13% of total ALL patients. Of them, 12 and 7 cases were diagnosed as L(1) and L(2) morphology respectively; 7 cases with balanced translocation of chromosome 1 and 19; 10 with der(19) t(1;19) formed from unbalanced translocation and 2 with normal karyotypes. TCF3-PBX1 fusion gene was detected by RT-PCR in 9 cases, and by iFISH in 17. 16 cases were B-phenotype and the other 2 T-phenotype; 17 cases had lymph node, spleen or liver infiltration. Of 18 patients received chemotherapy, 17 (94.7%) achieved complete remission (CR); the median relapse-free survival (RFS) and median overall survival was 3.2 months and 7.2 months, respectively.

CONCLUSIONSTCF3-PBX1-positive adult ALL had unique clinical and pathological features with high remission rate, high relapse rate and short survival time and should be considered to receive intensified treatment strategies. iFISH combined with CC and RT-PCR can increase the detection rate of t(1;19)/TCF3-PBX1 fusion gene.