Objective. A causative role for Epstein-Barr virus (EBV) in the development of lymphoma in patients with rheumatoid arthritis (RA) has been proposed. We investigated the molecular features of EBV-positive diffuse large cell lymphomas in 2 patients with RA.
Methods. Southern blot analysis for immunoglobulin gene rearrangements, terminal repeat analysis for clonality of the EBV genome, and double-labeling of the lymphoma cells by in situ hybridization and immuno-peroxidase staining were performed.
Results. In both cases, double-labeling studies localized the EBV genome to the malignant B cells. Both neoplasms contained clonal immunoglobulin gene rearrangements and clonal EBV genomes.
Conclusion. Our data indicate that EBV infection was an early step in the development of these neoplasms. The findings further extend knowledge on the similarity of this subset of lymphomas to posttransplantation lymphomas and emphasize the role of immunosuppression in their genesis.