Context.—

Plasmablastic lymphoma (PBL) is a rare aggressive lymphoma, usually positive for CD138 and frequently occurring in the oral cavity of human immunodeficiency virus (HIV) patients. Up to 10% of cases are negative for CD138 and diagnostically very challenging.

Objective.—

To investigate the appropriate approach to diagnose CD138 plasmablastic lymphoma and avoid misdiagnosis.

Design.—

We studied 21 cases of CD138 PBL from multiple large institutes in the United States and 21 cases from literature.

Results.—

CD138 PBLs were positive for different B/plasma cell markers at various percentages: MUM1 (94.4%; 34 of 36), OCT2 (70.6%; 12 of 17), immunoglobulin light chains (68.8%; 22 of 32), CD38 (68.4%; 13 of 19), CD79a (34.2%; 13 of 38), and PAX5 (15.6%; 5 of 32), suggesting that MUM1, OCT2, immunoglobulin light chains, and CD38 are useful markers to help establish the lineage. A total of 83% of cases (30 of 36) were extraoral lesions. Extraoral lesions showed much lower Epstein-Barr virus (EBV) infection rates (16 of 30; 53.3%) and had worse prognosis. MYC was positive in 80% (8 of 10) of EBV+ cases and 40% (2 of 5) EBV cases, indicating the importance of MYC in pathogenesis, especially in EBV+ cases.

Conclusions.—

Our study emphasizes that CD138 PBLs tend to be extraoral lesions, with much lower EBV infection rates, and diagnostically very challenging. Accurate diagnosis requires a thorough investigation and workup by using appropriate markers.

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Competing Interests

The authors have no relevant financial interest in the products or companies described in this article.