Epstein-Barr virus infection in Richter's transformation.

Chronic lymphocytic leukemia (CLL) may convert to a diffuse large cell lymphoma (Richter's syndrome) over time. In occasional cases of Richter's transformation, Epstein-Barr virus (EBV) has been identified in the lymphoma cells. To evaluate the association of EBV infection with Richter's syndrome, the biopsy specimens and clinical records of 25 patients who were seen at the Mayo Clinic between 1984-1996 were retrospectively evaluated for the presence of EBV by immunoperoxidase staining for expression of EBV latent membrane protein (LMP), as well as the expression of EBV RNA and DNA in the cells by in situ hybridization. Four of the 25 patients showed evidence of EBV in the diffuse large cell lymphoma cells-three patients with a B-cell phenotype were positive for LMP, EBV DNA, and RNA; and one patient with a T-cell phenotype had positive EBV RNA in the large cell lymphoma cells. The Richter's syndrome was treated with combination chemotherapy in 15 patients, three received radiotherapy, three were followed without further therapy after a splenectomy, two died before treatment could be started, and one patient had insufficient follow-up. One patient with evidence of EBV in large cell lymphoma cells was treated with acyclovir as initial therapy. The median survival of EBV-positive patients was three months compared with nine months for EBV-negative patients, but this difference was not statistically significant (P = 0.385). Evidence for EBV infection related to Richter's transformation was present in 16% of the patients in this study and may be associated with a poorer outcome. Primary therapy with acyclovir in one patient did not seem to be beneficial and other therapeutic modalities in patients with EBV-positive Richter's transformation need to be explored.