Immunophenotyping in the diagnosis of acute leukemias of ambiguous lineage. The results of centralized diagnosis and practical guidelines

   Acute leukemias of ambiguous lineage (ALAL) are rare acute leukemias (AL) that exhibit specific features of more than one hematopoietic lineage or show no distinct evidence of lineage differentiation. Immunophenotyping plays a key role in the diagnosis and classification of ALAL. Despite the availability of diagnostic criteria for ALAL proposed by different expert groups, the accurate diagnosis of ALAL representing a rare and heterogeneous group of diseases remains a challenge. In this paper, we present a brief analysis of 97 pediatric ALAL cases. Such a large cohort of cases with ALAL (ALALs comprising less than 1 % of all pediatric AL) was obtained as a result of the centralized diagnosis of AL. With regard to the obtained results, we have developed the guidelines for the interpretation of the results of immunophenotyping in the diagnosis of ALAL and for the integration of findings from flow cytometry, cytomorphology and genetic testing for the accurate diagnosis and classification of this group of AL.