Abstract

EBV-positive diffuse large B-cell lymphoma (DLBCL), not otherwise specified (NOS), is a clonal B-cell proliferation often occurring in patients older than 50 years old without known immunodeficiency or prior lymphoma. It was originally described as senile EBV-associated B-cell lymphoproliferative disorder, or EBV-positive DLBCL of elderly in the fourth edition of the WHO classification. Herein, we describe a 77-year-old female presenting with a left eyelid mass. MRI imaging of the left orbit showed a soft tissue mass measuring approximately 2.0 cm. Sections showed extensive geographic necrosis and sheets of large atypical lymphoid cells with vesicular chromatin, prominent nucleoli and moderate pale cytoplasm. By immunohistochemistry, tumor cells were diffusely positive for CD20, PAX5 and CD79a. BCL-6, BCL-2, MUM-1, C-MYC and CD30 immunostains were positive, while CD10 was negative. Ki67 proliferative index labeled >90% of tumor cells. EBER was diffusely positive by in situ hybridization. The overall findings were diagnostic of EBV-positive diffuse large B-cell lymphoma with double expressor and activated B-cell-like phenotype. FISH studies were negative for BCL6, MYC and IGH/BCL2 gene rearrangements. EBV-positive DLBCL accounts for 8-10% of DLBCL; however, little data are available regarding the incidence of this sub-type of DLBCL in western countries and in particular, when it presents as a periorbital soft tissue mass. While the pathogenesis is uncertain, immunological deterioration or senescence in immunity as part of the aging process are postulated mechanisms. Awareness of this sub-type of DLBCL is essential for accurate classification, appropriate treatment, and further elucidating the biology of this disease.

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