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. Latent membrane protein 1 positivity was detected by immunohistochemistry and Epstein-Barr-virus encoded small RNA positivity by chromogenic in situ hybridization. Clonality was confirmed by immunohistochemistry (kappa light-chain restriction), polymerase chain reaction (monoclonal immunoglobulin H gene rearrangement), and capillary electrophoresis (GeneScan). Staging procedures were negative. Withdrawal of methotrexate therapy led to complete remission within 6 weeks, and the patient is alive and disease-free 18 months after the diagnosis was made. The oral cavity is not often involved in the initial presentation of methotrexate-associated lymphoproliferative disorders, and presentation with intraoral ulcers is very rare. We have performed a review of the literature on methotrexate-associated lymphoproliferative disorders presenting as ulcers in the oral cavity.