Terminal deoxynucleotidyl transferase-negative acute lymphoblastic leukemia
J Faber1, H Kantarjian, M W Roberts
1Division of Pathology and Laboratory Medicine, Section of Hematopathology, The University of Texas M.D. Anderson Cancer Center, Houston, TX 77030, USA.
Archives of Pathology & Laboratory Medicine
|January 11, 2000
Summary
Three cases of T-cell acute lymphoblastic leukemia (ALL) were found to be negative for terminal deoxynucleotidyl transferase (TdT). This finding expands our understanding of TdT expression in lymphoid malignancies.
Area of Science:
- Hematology
- Oncology
- Immunology
Background:
- Terminal deoxynucleotidyl transferase (TdT) is a key marker for diagnosing acute lymphoblastic leukemia (ALL), particularly French-American-British (FAB) L1 and L2 subtypes.
- TdT is crucial for differentiating ALL from mature B-lymphoid neoplasms like Burkitt lymphoma (FAB L3) and other lymphoid cancers.
Observation:
- This study investigated the frequency of TdT-negative ALL, which is not well-established.
- Three cases of T-cell ALL meeting diagnostic criteria were identified as TdT-negative.
Findings:
- Despite being classified as early T-cell lineage ALL, these three cases showed no TdT positivity via immunofluorescence or flow cytometry.
- Flow cytometry confirmed a pre-T-cell immunophenotype in all three cases.
- Genetic analysis revealed T-cell receptor and immunoglobulin heavy chain gene rearrangements in one case, and immunoglobulin heavy chain rearrangement with T-cell markers in another.
Implications:
- The identification of TdT-negative T-cell ALL cases suggests that TdT negativity does not exclude this diagnosis.
- These findings may necessitate adjustments in diagnostic protocols for acute lymphoblastic leukemia.
- Further research is warranted to understand the clinical significance and frequency of TdT-negative ALL.
