Small intestinal follicular lymphoma induced by methotrexate: a case report

BACKGROUND: Methotrexate-associated lymphoproliferative disorder (MTX-LPD) is a rare but critical complication that develops in patients treated with MTX. Although MTX-LPD has been recently reported, the incidence of follicular lymphoma in the intestine is very low. CASE PRESENTATION: A 73-year-old woman who had been receiving MTX for over 10 years visited our hospital complaining of postprandial abdominal pain and nausea. Upper and lower digestive tract endoscopies did not show any abnormal findings. A patency capsule was stagnated at the proximal part of the ileum with a mild dilation on the oral side. An oral balloon endoscopy revealed shallow ulcerative lesions in the jejunum. She was diagnosed with MTX-LPD based on histopathological findings. The symptoms did not improve with the discontinuation of MTX, and the patient required partial resection of the small intestine. The test result for Epstein-Barr virus-encoded small RNA was negative. She was diagnosed with follicular lymphoma based on the histology findings of a surgical specimen. Postoperative positron emission tomography-computed tomography and bone marrow aspiration did not show any findings of lymphoma. On follow-up, no recurrence was noted four years after the surgery. CONCLUSIONS: Herein, we report the first case of follicular lymphoma that occurred in the small intestine, negative for Epstein-Barr virus-encoded small RNA. If intestinal symptoms occur during MTX administration, it is important to directly observe by endoscopy and perform histological examination.