CD3-positive plasmablastic lymphoma reported in two cases: A potential diagnostic caveat

Area of Science:

• Hematology
• Oncology
• Pathology

Background:

• Plasmablastic lymphoma (PBL) is an aggressive extranodal lymphoma, predominantly affecting the oral cavity in immunocompromised individuals.
• Diagnosis is challenging due to overlapping histopathological and immunophenotypic features with other large cell lymphomas.
• PBL typically lacks B-cell markers CD20 and CD79a but may express CD138.

Observation:

• This case series reports two instances of CD3-positive Plasmablastic Lymphoma in the oral cavity.
• These cases were initially misdiagnosed as high-grade T-cell lymphomas, including extranodal NK/T-cell lymphoma, nasal type.
• Aberrant CD3 expression in PBL, without other B-cell markers, is exceptionally rare and can lead to diagnostic errors.

Findings:

• CD3-positive PBL presents diagnostic challenges, mimicking T-cell lymphomas due to aberrant marker expression.
• Comprehensive evaluation including clinical presentation, histomorphology, immunohistochemistry, and molecular profiling is crucial for accurate PBL diagnosis.
• Distinguishing features are discussed to aid in differentiating PBL from other lymphomas.

Implications:

• Accurate diagnosis of CD3-positive PBL is critical to avoid misclassification and ensure appropriate therapeutic strategies.
• Understanding aberrant marker expression in PBL improves diagnostic accuracy and patient management.
• This study contributes to the literature on rare PBL variants, aiding pathologists and oncologists in recognizing and managing this aggressive lymphoma.