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[Relapse of biphenotypic leukemia confirmed by molecular study]
Masahiro Onozawa1, Satoshi Hashino, Koh Izumiyama
1Department of Gastroenterology and Hematology, Hokkaido University Graduate School of Medicine.
Insights
This study confirms biphenotypic leukemia relapse using T-cell receptor gene rearrangement analysis. This method also serves as a specific marker for minimal residual disease in leukemia patients.
Area of Science:
- Hematology
- Oncology
- Molecular Biology
Background:
- Biphenotypic leukemia presents a diagnostic challenge due to co-expression of lymphoid and myeloid markers.
- Relapsed leukemia requires accurate methods for distinguishing between new primary disease and recurrence of the original clone.
Observation:
- A 60-year-old woman presented with relapsed biphenotypic leukemia (ALL-L2) characterized by 53.5% lymphoblasts.
- Immunophenotyping showed lymphoblasts positive for both B-cell and myeloid lineage markers.
- Karyotype analysis revealed a normal chromosomal profile.
Findings:
- Polymerase chain reaction (PCR) detected a clonal rearrangement of the T-cell receptor (TCR) delta gene (TCR delta V delta 2-D delta 3).
- The identical TCR delta clonal rearrangement was identified in both the current relapse and initial leukemic cells.
- This confirmed the current leukemia as a relapse of the initial clone, not secondary leukemia.
Implications:
- T-cell receptor gene rearrangement analysis is a valuable tool for confirming leukemia relapse in biphenotypic leukemia.
- This patient-specific molecular marker can be utilized for sensitive detection of minimal residual disease.
- Accurate diagnosis of relapse is crucial for guiding appropriate treatment strategies and improving patient outcomes.
Abstract:
A 60-year-old woman was admitted to our hospital to receive treatment for relapse of biphenotypic leukemia 4 years after her initial presentation. Bone marrow examination revealed 53.5% lymphoblasts, which were classified as ALL-L2 with a normal karyotype. Lymphoblast surface markers were positive for cells of both B-cell and myeloid lineage. Immunoglobulin heavy chain and T-cell receptor gene rearrangements were investigated with PCR. Clonal rearrangement of TCR delta V delta 2-D delta 3 was detected. The same clonal rearrangement of TCR delta was found using frozen initial leukemic cells. Rather than secondary leukemia, the patient's leukemia was confirmed as relapse of the initial clone. Detection of the clonal rearrangement was also useful as a patient-specific marker for minimal residual disease.
