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Clonal B-cell lymphocytosis exhibiting immunophenotypic features consistent with a marginal-zone origin: is this a
Aliki Xochelli1, Christina Kalpadakis, Anne Gardiner
1Hematology Department and HCT Unit, G. Papanicolaou Hospital, Thessaloniki, Greece;
Insights
Clonal B-cell lymphocytosis of marginal-zone origin (CBL-MZ) is poorly understood but often remains stable. Chromosome 7q deletions were linked to stability, while complex karyotypes indicated progression, suggesting CBL-MZ may be a distinct entity.
Area of Science:
- Hematology
- Oncology
- Immunology
Background:
- The clinical significance of clonal B-cell lymphocytosis with a marginal-zone origin (CBL-MZ) is not well-defined.
- Existing classifications may not fully encompass these cases.
Purpose of the Study:
- To investigate the biological and clinical characteristics of CBL-MZ.
- To determine factors associated with disease progression.
Main Methods:
- Retrospective analysis of 102 CBL-MZ cases.
- Immunophenotyping, bone marrow biopsy, karyotyping, and immunogenetics were performed.
- Median follow-up of 5 years.
Main Results:
- Most cases (85/102) remained stable; 17 progressed, 15 developing splenomegaly.
- Chromosome 7q deletions were associated with stable disease (Group A).
- Complex karyotypes were more frequent in progressing cases (Group B).
Conclusions:
- CBL-MZ cases are often stable, potentially representing a distinct entity within marginal zone B-cell disorders.
- While CBL-MZ may precede splenic marginal zone lymphoma/small lymphocytic unclassifiable, its distinct clinical course warrants further investigation.
- Karyotypic abnormalities, specifically 7q deletions and complex karyotypes, may aid in predicting disease trajectory.
Abstract:
The biological and clinical significance of a clonal B-cell lymphocytosis with an immunophenotype consistent with marginal-zone origin (CBL-MZ) is poorly understood. We retrospectively evaluated 102 such cases with no clinical evidence to suggest a concurrent MZ lymphoma. Immunophenotyping revealed a clonal B-cell population with Matutes score ≤2 in all cases; 19/102 were weakly CD5 positive and all 35 cases tested expressed CD49d. Bone marrow biopsy exhibited mostly mixed patterns of small B-lymphocytic infiltration. A total of 48/66 (72.7%) cases had an abnormal karyotype. Immunogenetics revealed overusage of the IGHV4-34 gene and somatic hypermutation in 71/79 (89.8%) IGHV-IGHD-IGHJ gene rearrangements. With a median follow-up of 5 years, 85 cases remain stable (group A), whereas 17 cases (group B) progressed, of whom 15 developed splenomegaly. The clonal B-cell count, degree of marrow infiltration, immunophenotypic, or immunogenetic findings at diagnosis did not distinguish between the 2 groups. However, deletions of chromosome 7q were confined to group A and complex karyotypes were more frequent in group B. Although CBL-MZ may antedate SMZL/SLLU, most cases remain stable over time. These cases, not readily classifiable within the World Heath Organization classification, raise the possibility that CBL-MZ should be considered as a new provisional entity within the spectrum of clonal MZ disorders.
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