Epstein-Barr virus positive diffuse large B-cell lymphoma of the elderly.

Epstein-Barr virus positive diffuse large B-cell lymphoma (EBV+ DLBCL) of the elderly is a rare B-cell lymphoproliferative disorder (B-LPD) that occurs in patients > 50 years with no known history of immunodeficiency or lymphoma. Patients present with moderate to severe clinical B-symptoms. These lesions show complete effacement of normal tissue/nodal architecture by large atypical lymphoid cells/immunoblasts and Hodgkin/Reed-Sternberg-like giant cells with variable amounts of inflammatory cells in the background. The ratio of neoplastic to inflammatory cells, degree of mitoses and necrosis can be quite variable; hence EBV+ DLBCL of the elderly was historically divided into low grade polymorphic and high grade monomorphic types. Further studies have shown both types to be different points in the spectrum of disease, and are all high grade lymphomas. The neoplastic large lymphoid cells show expression of CD20/CD79a and PAX-5, with variable expression of CD30, LMP-1 and EBNA-2, but CD15, CD10 and BCL6 are generally negative. Neoplastic cells show EBER positivity and high Ki-67 expression. Differential diagnoses include EBV+ B-LPD, classical Hodgkin lymphoma and EBV-DLBCL. EBV+ DLBCL of the elderly is highly aggressive with a median survival of 2 years. These patients are less responsive to standard chemotherapy compared with other B-LPD.