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PAX5 and TDT-Negative B-Acute Lymphoblastic Leukemia with Unusual Genetic Mutations: A Case Report
B-acute lymphoblastic leukemia (B-ALL) is commonly encountered in clinical practice. Patients present with increased percentage of lymphoblasts in bone marrow and/or peripheral blood. Immunophenotypic study by flow cytometry or immunohistochemistry is essential to establish the diagnosis. Paired box-5 (PAX5) is a B cell lineage protein and terminal deoxynucleotidyl transferase (TDT) is an immature marker, both of which are routinely tested in the pathologic workup of acute leukemia. In this report, we describe a case of B-ALL in a 37-year-old woman in which both PAX5 and TDT were negative. Next-generation sequencing test detected mutations in DNA methyltransferase 3 α and Fms related receptor tyrosine kinase 3 genes, which are frequently mutated in acute myeloid leukemia rather than B-ALL. The constellation of these rare findings in a single case signifies the importance of examining a wide panel of markers when the diagnosis of ALL is suspected.
KeywordsALL - B-ALL - acute leukemia - TDT - PAX5 - immunohistochemistry - flow cytometry - DNMT3A - FLT3
Article published online:
21 December 2022
© 2022. Syrian American Medical Society. This is an open access article published by Thieme under the terms of the Creative Commons Attribution-NonDerivative-NonCommercial License, permitting copying and reproduction so long as the original work is given appropriate credit. Contents may not be used for commercial purposes, or adapted, remixed, transformed or built upon. (https://creativecommons.org/licenses/by-nc-nd/4.0/)
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