Mixed-phenotype acute leukemia characteristics: first report from Iran

Mixed-phenotype acute leukemia (MPAL) is the infrequent type of acute leukemia characterized by immunophenotypic and/or cytochemical features of both lineages, but the diagnosis of this disease still is a challenge. In this study, we analyzed immunophenotyping, cytochemistry and frequency of MPAL patients to better diagnosis of MPAL characteristics according to WHO 2016 criteria for the first time in Iran. In this retrospective study, 27 patients were diagnosed as MPAL based on WHO 2016 criteria during 2014-2017. Flow cytometric immunophenotyping was performed on PB and BM samples evaluation of different CD marker expressions in MPAL subsets. RT-PCR was performed for the analyses of BCR/ABL1 fusion in MPAL subsets. Among 27 cases, (70.4%) 19 cases were B + My, (22.22%) 6 cases were T + My, and 2 cases (7.40%) were B + T + My. CD34, CD19, HLA-DR, TdT, CD22, iMPO were positive in majority of B + My cases. CD45, iMPO, iCD3, CD7, CD2 and CD5 were positive in majority of T + My cases. HLA-DR, TdT, CD10, CD22, iCD79a, iMPO, CD45, iCD3, CD7, CD3, CD2, CD5 were positive in majority of B + T + My cases. BCR/ABL1 fusion was positive for 3 cases (11.1%) of p190 fusion and 2 cases (7.4%) of p210 fusion in B + My cases. WHO 2016 criteria are the current standard for diagnosing MPAL. Also, evaluation of TdT, CD2, CD5, CD7 expressions by flow cytometry in EGIL criteria is useful for the better diagnosis of MPAL subsets. In addition, evaluation of BCR/ABL1 and MLL rearrangements in patients should be part of standard work-up in MPAL.