Biphenotypic acute leukemia with t(15;17).

Biphenotypic acute leukemias (BAL) represent 5% of all acute leukemias. The most frequent cytogenetic abnormalities described are Philadelphia chromosome and 11q23 involvement. Here we report a BAL case, with blasts showing lymphoblast morphology and positivity for myeloperoxidase (in 6% of the blast cells). Immunophenotype revealed the compromise of myeloid and B-lymphoid lineages. Cytogenetic analysis showed the t(15;17) and 8 trisomy. PML/RARa rearrangement was detected by fluorescent in situ hybridization (FISH) on interphase nuclei while PML/RARa fusion transcript was detected in the bone marrow and peripheral blood by molecular biology studies (RT-PCR). This report describes a BAL case with an unfrequent cytogenetic abnormality, and highlights the importance of correlating the results of multiple diagnostic methods in order to establish a correct diagnosis and treatment in BAL patients.