Epstein Barr Virus Infection Can be a Secondary Event in B-Cell Lymphomas: A Review of 338 Cases and a Novel Finding of Zonal EBER+ Tumor Cells Showing Features of Progression From Underlying EBV-negative Lymphoma

Cases of B-cell lymphoma over an 8-year interval with diagnosis of EBER positivity were retrieved from archives and reviewed for classification and pattern of Epstein Barr Virus (EBV) expression. Of 46 cases that were EBV early RNA (EBER)+ by in situ hybridization staining, 7 had nonuniform staining among the neoplastic cells. Four of those cases showed a uniform admixture of EBER+ and EBER- tumor cells, compatible with the prevailing theory of episomal EBV loss with cell replication. Three cases of lymphomas showed a partial and zonal pattern and other features suggest that EBV infection occurred after the lymphoma was already established. In case 1, an EBV-negative follicular lymphoma and an EBV+ diffuse large B-cell lymphoma (DLBCL) of activated B cell type were contiguous in a lymph node. Both components showed a BCL2 translocation by fluorescence in situ hybridization. In case 2, a DLBCL of germinal center type in an human immunodeficiency virus positive patient contained clusters of EBR+ lymphoma cells with Reed-Sternberg morphology and shift to an activated B-cell immunophenotype. In case 3, an ulcerated and perforated DLBCL in the stomach showed a superficial swath of EBER+ tumor cells accompanied by a relative absence of reactive T cells. In all 3 cases the tumor cells in EBER+ areas expressed latent membrane protein-1 and showed strong CD30 positivity. All 3 patients were treated with chemotherapy are currently in remission. Heterogenous EBER positivity has been reported previously in DLBCLs, attributed to loss of the episomal viral DNA from a subset of fully transformed tumor cells. Previously reported cases did not include description of zonation of EBV or phenotypic differences correlating with the presence of EBV. The cases reported here suggest that in a subset of EBV+ DLBCLs, EBV infection may not be the "first hit."