Iraqi Journal of Hematology (Jan 2021)
Understanding mixed phenotypic acute leukemia: A conundrum of six cases with review of literature
Abstract
BACKGROUND: Mixed phenotype acute leukemias (MPALs) are a heterogeneous group of rare leukemias, with an incidence of 2%–5% of all acute leukemias and varied clinical, cytogenetic, immunophenotypic, and molecular genetic features. They have been reported to have a poor prognosis, early relapse, and increased incidence of extramedullary infiltration. MATERIALS AND METHODS: Retrospective analysis of all the acute leukemias (ALs) diagnosed in the department of pathology over the period of August 2017 to December 2019 was done. MPAL cases were identified in accordance with the World Health Organization (WHO) 2016 guidelines and European Group for the Immunological Classification of Leukemias Criterion. Beckman and Coulter FC500 flow cytometer was used using AL panel with CD3, cyCD3, CD5, CD1a, CD2, CD4, CD8, and CD7 as the markers for T-cell lymphoid lineage, along with CD19, CD 79a, CD22, and CD20 for B-cell lineage and CD13, CD33, CD 14, CD64, and myeloperoxidase for myeloid lineage/monocytic lineage. Molecular analysis was also done. RESULTS: Of the 153 cases newly diagnosed cases of AL during this period, 6 fulfilled the European group for immunological characterization of acute leukemia/WHO criteria for MPAL (3.9%). The age ranged from 3 to 13 years with male-to-female ratio of 1:1. Four out of the six cases (66.6%) were assigned B-lymphoid/myeloid type and two (33.3%) were assigned B/T lymphoid. Cytogenetics was available in four out of six cases, among which three had a normal karyotype and one had Breakpoint Cluster Region- Abelson Murine Leukemia 1 (Philadelphia chromosome) (BCR-ABL) translocation (t [9;22] [q34; q11]). CONCLUSION: Distinction at the outset is of paramount importance and the role of morphology, flow cytometry compounded with cytogenetic/molecular studies cannot be denied.
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