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PAX5 and TDT-Negative B-Acute Lymphoblastic Leukemia with Unusual Genetic Mutations: A Case Report
Tariq N Aladily1, Jamil F Qiqieh1, Alaa Alshorman2
1Department of Hematopathology, The University of Jordan, Amman, Jordan.
Insights
This case study highlights a rare B-acute lymphoblastic leukemia (B-ALL) presentation. Negative PAX5 and TDT markers, with mutations typically seen in AML, underscore the need for comprehensive diagnostic panels in leukemia.
Area of Science:
- Hematology
- Oncology
- Molecular Diagnostics
Background:
- B-acute lymphoblastic leukemia (B-ALL) diagnosis relies on lymphoblast identification.
- Immunophenotyping using markers like PAX5 and TDT is standard for B-ALL.
- PAX5 confirms B-cell lineage, while TDT indicates immaturity.
Observation:
- A 37-year-old woman presented with B-ALL.
- Paired box-5 (PAX5) and terminal deoxynucleotidyl transferase (TDT) were unexpectedly negative.
- Next-generation sequencing revealed mutations in DNMT3A and FLT3 genes.
Findings:
- The patient's B-ALL lacked typical B-cell markers (PAX5, TDT).
- Detected mutations (DNMT3A, FLT3) are more common in acute myeloid leukemia (AML).
- This represents a rare molecular and immunophenotypic profile for B-ALL.
Implications:
- This case emphasizes the diagnostic challenges posed by atypical B-ALL.
- A broad range of markers is crucial for accurate leukemia subtyping.
- Rethinking diagnostic algorithms for B-ALL may be necessary in complex cases.
Abstract:
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.
