Biphenotypic acute leukemia

Biphenypic leukemia (BAL) is defined by the presence on the same blastic cells of markers belonging to at least two different lines. The incidence is estimated at less than 5% of acute leukemia cases, even if there are disparities in the literature. The morphological aspects of blast cells are variable, aspects of lymphoblasts in 1/3 cases or myeloblasts in other cases. Blast cell flow cytometry distinguishes BAL with co-expression of lymphoid and myeloid markers (L+M) or myeloid markers with lymphoid markers (M+L). BAL with lymphoid markers B and T (B+T) are rarer. Conventional cytogenetic examination makes it possible to highlight more frequently in the BAL type anomalies t(9;22)(q34;q11) in adults, t(12;21)(p13;q22) in children or abnormalities in 11q23, more rarely other cytogenetic abnormalities. We note the observation of two cases of acute leukemia with their immunophenotypic profile in order to highlight the difficulty of classifying certain acute leukemia with a mixed phenotype and highlight the complementarity of biological analyses for characterization and management of these leukemias.