[Methotrexate-associated lymphoproliferative disorder presenting as oral ulcers in a patient with rheumatoid arthritis].

Methotrexate-associated lymphoproliferative disorders are a heterogeneous group of lymphoid proliferations or lymphomas that develop in patients with autoimmune diseases treated using methotrexate. These lymphoproliferative disorders are often associated with Epstein-Barr virus infection and occasionally regress after the withdrawal of methotrexate therapy. The lymphoproliferative disorder in this case was diffuse large B-cell lymphoma, unusually presenting as oral ulcers in a 79-year-old woman on treatment with methotrexate for longstanding rheumatoid arthritis.