Lymphoproliferative disorder with pathological fracture of the femur in a patient with rheumatoid arthritis treated with methotrexate: A case report.

Methotrexate (MTX) is the key drug for the treatment of rheumatoid arthritis (RA). MTX-treated RA has been associated with the development of lymphoproliferative disorders (LPDs). Notably, the hyperimmune state of RA itself or the immunosuppressive state induced by MTX administration may contribute to development of LPD. Furthermore, Epstein-Barr virus (EBV) has been indicated to contribute to the development of MTX-LPD. MTX-associated LPD (MTX-LPD) may affect nodal or extranodal sites, including the gastrointestinal tract, skin, lungs, kidneys, and soft tissues, at an almost equal frequency. However, it is rare for MTX-LPD to manifest as multiple bone tumors with a pathological fracture. The present study reported the case of a 46-year-old Japanese woman with RA who had complications of EBV-positive MTX-LPD during an approximate 5-year course of MTX therapy. The present study indicated a rare case in which the LPD had spread to multiple bones in a patient with a pathologic fracture. Notably, the LPD was subclassified as diffuse large B-cell lymphoma (DLBCL).