Abstract
Subjects with rheumatoid arthritis (RA) risk developing malignant lymphoproliferative disorder, although why remains controversial, immunosuppresive therapy—specifically low-dose methotrexate (MTX)- and Epstein-Barr virus infection are suspected of contributing to this risk. Widely used to treat RA, MTX has been suggested in several studies to increase malignant lymphoma risk. A 75-year-old man with RA and treated 9 years with MTX suffered right neck lymphoid node and tonsil swelling that eventually developed into an ulcer. Blood chemistry findings showed elevated lactic dehydrogenase (LDH) and soluble IL-2 receptor. Enhanced computed tomography (CT) confirmed bilateral neck lymph node and right-tonsil swelling.
Histopathologically, he was diagnosed with diffuse large B-cell lymphoma in neck lymph node biopsy with EBER-1. Clinically, he was diagnosed with MTX-associated lymphoproliferative disorder (MTX-LPD). MTX was discontinued 2 weeks after, his sore throat had disappeared, and CT 40 days later showed that all lesions also had disappeared. His clinical course continues to be good with no sign of recurrence.
