抄録
Methotrexate-associated lymphoproliferative disorder （MTX-LPD） is a lymphoproliferative disorder that occurs in patients taking MTX. Although it is rare to occur in the oral cavity, reports of MTX-LPD have occurred occasionally in recent years. Maxillary gingiva is the most frequently reported site in the oral cavity; lips being affected is rarely reported. This time, we experienced a case of MTX-LPD in the corner of the mouth. The case is a woman in her 60s. She had a history of rheumatoid arthritis and osteoporosis and had been taking methotrexate for 11 years. At the first visit, findings that may have been malignant were observed from the right corner of the mouth to the lower lip, but the examination was conducted with the possibility of MTX-LPD in mind. As a result of a biopsy, MTX-LPD was diagnosed, and improvement was observed only by discontinuing MTX. In this case, we suspected MTX-LPD from the beginning for a case with suspected oral cancer in the corner of the mouth, and we were able to treat it early by diagnosing MTX-LPD by examination. Since the clinical symptoms of MTX-LPD are diverse, it is considered necessary to make a diagnosis with this disease in mind for patients taking MTX.
