[A Case of Small Bowel Perforation Caused by Malignant Lymphoma after Methotrexate Therapy for Rheumatoid Arthritis].

A 73-year-old woman had a history of medication, including methotrexate for rheumatoid arthritis, for 5 years. She had chronic epigastralgia for 2 weeks and found to have multiple submucosal tumors on upper gastrointestinal endoscopy in another hospital. She had a strong abdominal pain thereafter and diagnosed as having gastrointestinal perforation on the basis of CT scans. Abdominal examination revealed disseminated peritonitis, and emergency laparoscopic surgery was performed on the day of admission. A 1 cm perforation of the ileum was identified, and a 5 cm mass of the mesentery near the perforation was also identified. Small bowel partial resection, including both lesions, was performed. From the intraoperative findings, methotrexate-associated lymphoproliferative disorders(MTX-LPD)was suspected, and methotrexate was discontinued after the surgery. At a later date, the pathological result from both the surgical specimen and upper gastrointestinal endoscopy was diffuse large B cell lymphoma(DLBCL). CT scan, PET-CT scan, and upper gastrointestinal endoscopy were performed 1-2 months after surgery, and no tumor was identified. Currently, 6 months after the surgery, the patient is still alive without any progression of the lymphoma.