Mixed phenotypic acute leukemia (B/T), with t(9;22)(q34;q11.2);BCR-ABL1: a rare phenomenon and strange phenotype

Mixed phenotypic acute leukemia (MPAL) is an uncommon hematological neoplasm which can either contain distinct blast populations, each of a different lineage (bilineal) or one population with multiple antigens of different lineage on the same cells (biphenotypic). t(9;22)(q34;q11.2;BCR-ABL1) is the most common recurrent genetic abnormality in MPAL; however, it is a very rare leukemia that accounts for less than 1 % of all acute leukemias and is usually associated with poor outcome. Common phenotypic expression of MPAL includes T/Myeloid and B/Myeloid. Leukemic blast showing evidence of both B and T lineage commitment has been described as a very rare phenomenon in the existing literature. We here report a rare case of MPAL (B/T lineage) with t(9;22)(q34;q11.2;BCR-ABL1) along with morphologic and immunophenotypic findings with special emphasis on need to differentiate such cases from patients with CML-Blast crisis as therapy, and prognosis in these two scenarios differ significantly.