Effects of a biologic agent in a patient with rheumatoid arthritis after treatment for methotrexate-associated B-cell lymphoma: a case report

BACKGROUND: Several studies have suggested an increased risk of malignant tumor in patients with rheumatoid arthritis. It has been also reported that rheumatoid arthritis patients have a high incidence of lymphoma compared with the general population, and that patients receiving methotrexate, which is the anchor drug for rheumatoid arthritis treatment, can develop lymphoproliferative disease. Nevertheless, management of rheumatoid arthritis after treatment for methotrexate-associated lymphoma has not been fully investigated. We here report a patient with rheumatoid arthritis who developed malignant lymphoma associated with methotrexate therapy. Moreover, we describe the use of a biologic agent for a rheumatoid arthritis patient after treatment for lymphoma associated with methotrexate. CASE PRESENTATION: A 60-year-old Japanese man with a 20-year history of rheumatoid arthritis was admitted to our hospital with a left inguinal tumor. Open biopsy was performed and a biopsy specimen revealed diffuse large B-cell lymphoma. As our patient had received methotrexate for 4 years, we diagnosed the lymphoproliferative disease as being methotrexate-related. This lymphoma was not associated with Epstein- Barr virus by Epstein-Barr virus-encoded ribonucleic acid in-situ hybridization, but this patient was an Epstein-Barr virus carrier, regarding serological testing. The lymphoma went into complete remission after 6 courses of rituximab plus cyclophosphamide, hydroxydaunorubicin, vincristine, and prednisone/prednisolone therapy. Two years later, however, rheumatoid arthritis activity gradually increased and was not controlled with salazosulfapyridine. Etanercept was administered in view of its possible effect on B-cells, and this reduced the level of disease activity without recurrence of lymphoma. CONCLUSION: The management of rheumatoid arthritis after treatment for methotrexate-associated lymphoma has not been fully investigated yet. Etanercept appeared to be safe because of its B-cell effect, but further observation is necessary to make a firm conclusion. Further accumulation of cases is needed to clarify which biologics are safe and effective for treatment of methotrexate-associated B-cell lymphoma.