Polymorphic lymphoproliferative disorders in patients with rheumatoid arthritis are associated with a better clinical outcome

The characteristics of lymphoproliferative disorders (LPD) in patients with rheumatoid arthritis (RA) remain unclear. Therefore, we retrospectively analyzed the clinical characteristics of these patients in our department.Twenty RA patients who developed LPD between April 2003 and August 2016 in our department were analyzed.All of the RA patients who developed LPD had been treated with methotrexate (MTX). The median weekly and total dosages of MTX were 6.8 mg/week and 2530 mg, respectively. The median duration of MTX administration was eight years. Nineteen patients (95%) achieved complete remission (CR) and 15 (75%) achieved CR with MTX cessation alone. Based on the pathological findings, we divided MTX-associated LPD patients into two groups (n = 16); polymorphic LPD (31%) and other groups. CR with MTX cessation alone was achieved in 5 (100%) and 6 (54.5%) patients in the polymorphic LPD and other groups, respectively (p = .12). Moreover, the duration from the cessation of MTX to CR was significantly shorter in the polymorphic LPD group than in the other group (5.3 months vs 12.6 months, p = .01, respectively).Polymorphic LPD, which was the most frequent pathological diagnosis in this cohort, was associated with a higher incidence of CR and a significantly shorter duration to CR.