Atypical lymphoproliferation progressing into B-cell lymphoma in rheumatoid arthritis treated with different biological agents: clinical course and molecular characterization.

A patient with rheumatoid arthritis (RA) developed an atypical lymphoproliferative disorder (LPD) after methotrexate and cyclosporine A, which regressed after suspension of both drugs. After subsequent treatment with rituximab, the LPD was still undetectable. Anti-tumor necrosis factor a therapy was used when the arthritis relapsed, but an aggressive B-cell non Hodgkin's lymphoma developed. Molecular analyses showed an oligoclonal B-cell expansion at the LPD step. A minor clone with significant sequence homology to B-cell lymphomas arising in Sjogren's syndrome and mixed cryoglobulinemia syndrome, given rise to the non-Hodgkin's lymphoma. Treatment of rheumatoid arthritis associated with lymphoproliferation represents a clinical challenge, and common pathogenetic pathways to lymphoma may occur in different autoimmune diseases.