Immunophenotype, microRNA expression and cytogenetic characterization of acute leukemias of ambiguous lineage

Acute leukemias of ambiguous lineage (ALAL) form a group of leukemias presenting the features of both acute lymphoid leukemia (ALL) and acute myeloid leukemia (AML). Based on Immunologic Classification of Leukemia (EGIL), these leukemias are recognized as biphenotype acute leukemia (BAL). According to WHO classification and based on immunophenotypic characteristics, ALAL is further categorized to acute undetermined leukemia (AUL), mixed phenotype acute leukemia (MPAL), and other ambiguous lineage leukemias. Immunophenotype and cytogenetic aspects are important in recognition of these leukemias; however, there is limited data about these leukemias. This has resulted in mistreatment of patients. Thanks to the recent advances and introducing the role of microRNAs in regulation of gene expression, a new avenue has been opened in the field of classification and pathogenesis of ambiguous lineage leukemias. MiRNA-based classification can help define myeloid or lymphoid origin of ambiguous lineage leukemias. Taking immunophenotype, cytogenetic, and miRNA profiles into account collectively, a better recognition of the disease is achieved, which results in accurate diagnosis and effective treatment of patients. In this review, we have discussed ambiguous lineage leukemias with regard to microRNA expression, immunophenotype, and cytogenetic aspects.