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Acute promyelocytic leukemia (APL) is characterized by the reciprocal translocation t(15;17)(q22;q21), resulting in the fusion of the promyelocytic leukemia gene at 15q22 with the retinoic acid receptor α at 17q21. Additionally, all patients with APL who have additional chromosome abnormalities (ACA) and gene mutations are resistant to all-trans retinoic acid (ATRA), the drug that causes disease regression specifically in patients with APL globally. The present study describes a case of a 19-year-old female with APL carrying a novel complex variant translocation t(6;17;15)(p21;q21;q22), add(7)(q32) and an FMS-related tyrosine kinase 3 internal tandem duplication (FLT3-ITD) mutation. Complete remission was attained following a course of chemotherapy with ATRA and arsenic trioxide. To the best of our knowledge, this is the first report of a novel three-way translocation of 6p21 and a FLT3-ITD mutation involved with APL.

This study was aimed to investigate the application value of the dual color dual fusion fluorescence in situ hybridization (DCDF-FISH) in BCR/ABL (+) acute lymphoblastic leukemia patients with complex chromosomal translocation. The clinical presentations of a patient with ALL were monitored regularly by bone marrow cell morphology test, chromosome analysis, flow cytometry and DCDF-FISH technique, and the reaction of patients to treatment and disease progression were dynamically observed by DCDF-FISH. The results indicated that the patient showed the typical presentation of B lineage acute lymphoblastic leukemia (B-ALL) with expression of CD10, CD19 and CD34; the chromosome analysis showed 46,XY, i(8), ider(9)t (9; 22) [23]/47, idem, +der(22) t (9;22) [7] karyotype in the bone marrow cells, FISH showed that 83% cells contained BCR/ABL fusion gene in the patient's bone marrow, among which 5% cells showed 1R1G2F signalling model, 14% cells showed 1R1G3F, and 64% cells showed 1R1G4F. The patient got complete remission when the imatinib chemotherapy combined with VTLP was carried out, and the tumor cells decreased to 19%, but the cells with 1R1G2F signal model increased to 18%. The 1R1G2F cell signal model increased up to 38% when patient relapsed. The patient died of the drug-resistance. It is concluded that the BCR/ABL (+) leukemia patient with complex translocation has multiple tumor cell subsets, and the responses of different cell subsets to the treatment are different, therefore the response to therapy and drug resistance of patient can be monitored early by the signal model of DCDF-FISH and the observation of dynamical changes of different cell subset.