Laboratory characterization of the pediatric B/T subtype of mixed-phenotype acute leukemia: Report of a case series.

Objectives: Mixed-phenotype acute leukemia (MPAL) is a rare disease associated with difficulties in the correct lineage assignment of leukemic cells. One of the least common subtypes within this category is characterized by the simultaneous presence of B- and T-lineage-defining antigens. Each case of suspected B/T MPAL should be considered in light of all available laboratory and clinical data to avoid misdiagnosis.
Methods: In this study, we describe 6 pediatric patients who presented with leukemic blasts bearing B- and T-lineage antigens at diagnosis, including their clinical, immunophenotypic, morphologic, and cytogenetic characteristics.
Results: In 3 patients, more or less distinct populations of B- and T-lymphoid origin were found; the other 3 patients had a single mixed-phenotype blast population. All cases fulfilled the World Health Organization criteria, but not all of them turned out to be bona fide cases of B/T MPAL according to the available clinical and laboratory data. Found genetic lesions were helpful for the confirmation of MPAL instead of 2 concomitant tumors, but for a general B/T MPAL diagnosis, genetic studies provided the only descriptive data.
Conclusions: The accurate diagnosis of B/T MPAL requires a multidisciplinary approach combining high-tech laboratory methods and close cooperation between treating physicians and pathologists.
(© The Author(s) 2024. Published by Oxford University Press on behalf of American Society for Clinical Pathology. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)