Plasmablastic lymphoma of the oral cavity in an HIV-negative patient.

Plasmablastic lymphoma (PBL) is a rare, highly aggressive lymphoma typified by immunoblast-like cells with abundant basophilic cytoplasm and paranuclear hof. It shows absent expression of CD45 and CD20. In contrast, it displays a constant reaction with CD138 and VS38c. It may be easily misinterpreted as some other lymphoma. An exhaustive integration of clinical, morphologic, phenotypic, and molecular features is important to exclude misdiagnosis and inappropriate treatment. We report a case of HIV-negative PBL arising on the left areas of posterior teeth mucosa of a 58-year-old man. Immunohistochemically, the tumor cell was immunoreactive for CD138, VS38c, VEGF, and vimentin; Ki-67 showed a high proliferation rate. Epstein-Barr virus (in situ hybridization) was nonreactive, and IgH gene rearrangement was identified by polymerase chain reaction amplification products. A diagnosis of PBL was rendered.