Composite lymphoma: a unique case with two immunologically distinct B-cell neoplasms

Area of Science:

• Hematology
• Oncology
• Immunology

Background:

• Rheumatoid arthritis (RA) is a chronic autoimmune disease.
• Autoimmune conditions are associated with an increased risk of certain malignancies.
• Lymphomas can arise in the context of chronic inflammation and immune dysregulation.

Observation:

• A unique case of composite lymphoma was observed in a 69-year-old male patient with severe, long-standing rheumatoid arthritis.
• The lymphoma involved a single axillary lymph node.
• The neoplasm exhibited a dual B-cell lymphoma morphology: nodular poorly differentiated lymphocytic lymphoma (IgG-kappa) and diffuse well-differentiated lymphocytic lymphoma (IgM-lambda).

Findings:

• Immunohistologic studies confirmed the simultaneous presence of two distinct monoclonal lymphocyte proliferations within the lymph node.
• This composite lymphoma comprised two separate B-cell lymphomas with different immunoglobulin light chain expressions (kappa and lambda).
• The findings underscore the diagnostic challenge posed by composite lymphomas, which may be missed without advanced immunophenotyping.

Implications:

• This case highlights a potential link between long-standing autoimmune disease, such as rheumatoid arthritis, and the development of composite lymphomas.
• Immunohistochemistry is essential for accurate diagnosis and characterization of composite lymphomas, differentiating them from single lymphomas.
• Further research is warranted to elucidate the specific mechanisms by which autoimmune conditions may contribute to the genesis of such complex lymphoid malignancies.