Epstein-Barr Virus-Positive CD20- and CD45-Negative Diffuse Large B-Cell Lymphoma: A Diagnostic Challenge

Area of Science:

• Hematology
• Oncology
• Immunopathology

Background:

• Diffuse large B-cell lymphoma (DLBCL) typically expresses B-cell markers like CD20 and CD45.
• A rare subset of DLBCL lacks CD20 expression, including specific subtypes like primary effusion lymphoma and plasmablastic lymphoma.
• Distinguishing these rare DLBCL variants from other lymphomas is crucial for accurate diagnosis and treatment.

Purpose of the Study:

• To report a rare case of Epstein-Barr virus-positive DLBCL that was negative for both CD20 and CD45.
• To highlight the diagnostic challenges posed by this unusual DLBCL subtype.
• To demonstrate the utility of specific B-cell markers in diagnosing such cases.

Main Methods:

• Immunohistochemical analysis was performed on neoplastic cells.
• The study ruled out known CD20-negative DLBCL subtypes.
• Diagnostic confirmation relied on B-cell transcription factor Oct-2 and pan-B cell marker CD79a expression.

Main Results:

• A case of Epstein-Barr virus-positive DLBCL lacking CD20 and CD45 expression was identified.
• The patient's lymphoma did not fit the criteria for other established CD20-negative DLBCL entities.
• Immunoreactivity for Oct-2 and CD79a supported the diagnosis of Epstein-Barr virus-positive DLBCL.

Conclusions:

• Epstein-Barr virus-positive DLBCL can present as a rare CD20- and CD45-negative entity.
• Diagnostic workup for unusual DLBCL requires careful consideration of immunophenotype and exclusion of other subtypes.
• Oct-2 and CD79a are valuable markers for identifying this rare DLBCL variant.