Lymphoproliferative disorders in rheumatoid arthritis: clinicopathological analysis of 76 cases in relation to methotrexate medication.

Individuals with rheumatoid arthritis (RA) with or without methotrexate (MTX) medication occasionally develop lymphoproliferative disorders (MTX-LPD and non-MTX-LPD, respectively). The hyperimmune state of RA itself or the immunosuppressive state induced by MTX administration might contribute to development of LPD. Our objective was to characterize MTX-LPD in comparison to non-MTX-LPD and sporadic LPD in patients with RA. We compared MTX-LPD to non-MTX-LPD and sporadic LPD by evaluating 48 cases of MTX-LPD, 28 non-MTX-LPD, and 150 sporadic LPD. Later onset age of LPD and female predominance were evident in patients with RA-LPD compared to sporadic LPD. The interval between the diagnosis of RA and LPD in MTX-LPD (median 132 mo) was significantly shorter than that in non-MTX-LPD (240 mo). The frequency of diffuse large B cell lymphoma (DLBCL) and positive rate of Epstein-Barr virus (EBV) in RA-LPD was significantly higher than in sporadic LPD (57.9% vs 42.7%, 27.6% vs 9.9%, respectively). After withdrawal of MTX, 11 of the MTX-LPD cases showed a spontaneous regression of tumors. The 5-year survival rate in RA-LPD (59.2%) was significantly worse than that in sporadic LPD (74.6%). The majority of cases of RA-LPD show similar clinicopathological characteristics irrespective of MTX medication, except for spontaneous regression of LPD after withdrawal of MTX in MTX-LPD, and a shorter interval between the diagnosis of RA and LPD in MTX-LPD than in non-MTX-LPD. RA-LPD cases showed younger age of onset, female predominance, unfavorable prognosis, and higher frequencies of DLBCL and EBV positivity compared to sporadic LPD.