Surface Light Chain Expression in Primary Mediastinal Large B-Cell Lymphomas by Multiparameter Flow Cytometry.

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.