- 社団法人 日本口腔外科学会
- 日本口腔外科学会雑誌 (ISSN:00215163)
- vol.55, no.9, pp.463-466, 2009-09-25 (Released:2012-08-28)
Methotrexate (MTX) has been proven to be effective for the treatment of rheumatoid arthritis (RA)and is believed to be nononcogenic when a low weekly dose is administered to patients with RA. However, wereport the case of a 71-year-old man with RA who was treated for 11 years with MTX and developed B cell non-Hodgkin's lymphoma (BNHL) in the oral cavity. The tumor was localized in the right maxilla extranodally.Microscopic examination of a biopsy specimen revealed a non-epithelial tumor pattern and showed BNHL inwhich large cells with pleomorphic nuclei invaded the muscle tissue. These large cells tested strongly positive forEpstein-Barr virus encoded small RNAs-in situ hybridization (EBER-ISH) and CD20 antibody. We immediatelystopped MTX administration; however, only minimal shrinkage of the tumor was observed. Therefore, we performedantibody treatment with rituximab. After chemotherapy, complete remission was achieved. To date, thepatient is healthy, with no evidence of tumor recurrence during 32 months of follow-up. The development of anextranodal lymphoma in the oral cavity in a patient with RA who received MTX has not been reported previously.Therefore, this case is considered extremely rare.