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CD20-positive T-cell chronic lymphocytic leukaemia
British Journal of Haematology
|September 30, 1998
Summary
This study reports the first case of clonal expansion in CD20-dim T lymphocytes, a rare finding in T-cell malignancies. This discovery challenges traditional B-cell markers and expands understanding of T-cell neoplasms.
Area of Science:
- Hematology
- Immunology
- Oncology
Background:
- CD20 is a well-established B lymphocyte marker.
- A small subset of normal T lymphocytes can express CD20 weakly.
Observation:
- A 60-year-old man presented with pancytopenia and hepatosplenomegaly.
- Atypical lymphocytes showed weak CD20 expression and T-cell antigen positivity.
Findings:
- The leukaemic cells were positive for T-cell antigens (CD2, CD3, CD5, CD7, CD8, TCR Vbeta8) and activation markers (CD38, HLA-DR).
- Cells were negative for B-cell markers (CD19, CD21, CD22, CD25).
- TCR-beta gene rearrangement and germline immunoglobulin heavy chain gene confirmed T-cell origin.
Implications:
- This is the first documented case of clonal expansion of CD20-dim T lymphocytes.
- Highlights the importance of comprehensive immunophenotyping in diagnosing T-cell malignancies.
- May necessitate re-evaluation of CD20 as a strictly B-cell lineage marker in certain contexts.