Retrospective Study of 68 Patients with Rheumatoid Arthritis-Associated Lymphoproliferative Diseases Treated with Methotrexate

Objectives This study aimed to investigate the clinical features of lymphoproliferative disease (LPD) in rheumatoid arthritis (RA) patients. Methods We examined the reasons for methotrexate (MTX) discontinuation in 829 patients with RA. In 68 patients with RA whose reason for discontinuation was suspected LPD, blood test results and patient background on the day of MTX discontinuation, pathological characteristics, and the use of biologics after the diagnosis of LPD were analyzed. Results In 829 RA patients in whom MTX was discontinued during the course of treatment, suspected LPD was the fourth most common reason for discontinuation (n=68). Patients who discontinued MTX due to suspected LPD were significantly older and had lower lymphocyte counts, higher serum LDH levels, lower serum albumin levels, higher serum CRP levels, and higher serum soluble interleukin-2 receptor (sIL-2R) levels than patients who discontinued MTX for other reasons. In patients who discontinued MTX due to suspected LPD, the MTX dose used at the time of MTX discontinuation was significantly higher in patients whose lesions regressed spontaneously with MTX discontinuation alone than in patients whose lesions required treatment due to a lack of regression or who died. During the observation period, 16 patients received biologics after LPD regression. LPD did not relapse during the observation period. Conclusions Biologics might be an effective choice for patients with RA after LPD regression, but their safety has not been fully evaluated. Therefore, careful follow-up is required.