Surface Light Chain Expression in Primary Mediastinal Large B-Cell Lymphomas by Multiparameter Flow Cytometry
Olga K Weinberg1, Scott J Rodig2, Olga Pozdnyakova2
1From the Boston Children's Hospital, Boston, MA; Olga.Weinberg@childrens.harvard.edu.
Insights
Primary mediastinal large B-cell lymphoma (PMLBL) can present with clonal surface light chain expression in 50% of cases. This finding highlights PMLBL
Area of Science:
- Hematology
- Oncology
- Immunophenotyping
Background:
- Primary mediastinal large B-cell lymphoma (PMLBL) is an aggressive lymphoma.
- Comprehensive multiparameter flow cytometry analysis of PMLBL is lacking.
Purpose of the Study:
- To conduct a comprehensive flow cytometry analysis of PMLBL.
- To investigate the immunophenotypic diversity of PMLBL.
Main Methods:
- Retrospective review of PMLBL cases with diagnostic flow cytometry.
- Multi-institutional data collection from Boston Children's Hospital, Brigham and Women's Hospital, and Stanford Hospital.
Main Results:
- PMLBL predominantly affects women (median age 30 years) with stage 1 disease and no bone marrow involvement.
- 50% of PMLBL cases exhibited restricted surface immunoglobulin expression by flow cytometry.
- Absence or presence of surface light chains did not correlate with morphology, immunophenotype (CD23, CD30, CD10), age, or stage, and showed similar survival outcomes.
Conclusions:
- PMLBL exhibits greater immunophenotypic diversity than previously recognized.
- Clonal surface light chain expression occurs in 50% of PMLBL.
- Surface light chain expression should not be the sole diagnostic criterion for PMLBL.
Objectives:
Primary mediastinal large B-cell lymphoma (PMLBL) is an aggressive B-cell lymphoma typically localized to the mediastinum. To date, no study has undertaken a comprehensive analysis of this entity by multiparameter flow cytometry.
Methods:
Cases of PMLBL with diagnostic flow cytometry were identified from pathology databases of Boston Children's Hospital, Brigham and Women's Hospital, and Stanford Hospital.
Results:
Most of these patients with PMLBL were women with a median age of 30 years who had stage 1 disease that lacked bone marrow involvement. By flow cytometry, 50% of all PMLBLs showed restricted surface immunoglobulin expression. When comparing patients with PMLBL by the absence or presence of surface light chain immunoglobulins, no differences were seen in the morphologic appearance; expression of CD23, CD30, or CD10; age at presentation; or clinical stage (P > .5 for all). In addition, both groups showed similarly good survival outcomes and were alive at last follow-up (11/14 [79%]; P = .542).
Conclusions:
This multi-institutional study demonstrates that 50% of PMLBLs can present with clonal surface light chain expression and that PMLBL is more immunophenotypically diverse than previously described. Furthermore, our findings suggest that the absence or presence of surface light chains should not be used as criteria for diagnosis in this disease.
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