Prominent clonal B-cell populations identified by flow cytometry in histologically reactive lymphoid proliferations
Steven J Kussick1, Michael Kalnoski, Rita M Braziel
1Department of Laboratory Medicine, University of Washington, Seattle, USA.
Insights
Clonal B-cell populations can appear in reactive follicular hyperplasia, mimicking lymphoma. This study identified such cases, showing no lymphoma development in patients with these findings.
Area of Science:
- Hematopathology
- Immunology
- Oncology
Background:
- Clonal B-cell populations are typically associated with lymphoma.
- Follicular hyperplasia is a reactive process in lymph nodes.
- Distinguishing reactive hyperplasia from lymphoma is crucial for diagnosis.
Purpose of the Study:
- To describe cases of apparent clonal B-cell populations in histologically reactive lymph nodes.
- To investigate the clinical significance of these findings.
- To differentiate reactive follicular hyperplasia from neoplastic processes.
Main Methods:
- Flow cytometry analysis of B-cell populations.
- Molecular methods for clonality confirmation.
- Histologic examination of lymph node and tonsil biopsy specimens.
- Clinical follow-up of affected patients.
Main Results:
- Six cases showed prominent, clonal, CD10+ B-cell populations in reactive follicular hyperplasia.
- Histology lacked evidence of bcl-2 overexpression or t(14;18) translocation.
- No lymphoma developed in patients during follow-up (13-56 months).
- Cases occurred predominantly in young males and one HIV-positive woman.
Conclusions:
- Clonal B-cell populations can be present in benign, reactive follicular hyperplasia.
- These findings highlight the importance of integrating flow cytometry, molecular, and histologic data.
- Careful evaluation is needed to avoid misdiagnosis of lymphoma in such cases.
Abstract:
We describe 6 cases from the University of Washington Hematopathology Laboratory (Seattle) in which prominent, clonal, follicle center B-cell populations were identified by flow cytometry and confirmed by molecular methods, but in which the histologic features showed reactive follicular hyperplasia without evidence of bcl-2 overexpression or the t(14;18). The 6 cases included 5 lymph node biopsy specimens and 1 tonsillectomy specimen. Of the 6 cases, 5 occurred in young males (8-28 years) with no known immunologic abnormality; the other case was a 32-year-old, HIV-positive woman. In all 6 cases, clonal CD10+ B cells representing at least 20% of the total B cells were identified. Available clinical follow-up ranging from 13 to 56 months revealed no evidence of lymphoma in any of the 6 patients. Our findings add rare cases of follicular hyperplasia to the list of histologically reactive settings in which clonal B-cell populations might be present.
