Endoscopic Visualization of a Jejuno-Colonic Fistula in a Case of Monomorphic Epitheliotropic Intestinal T-Cell Lymphoma.

Monomorphic epitheliotropic intestinal T-cell lymphoma (MEITL) is a rare primary intestinal T-cell lymphoma newly defined in the 2016 WHO classification, characterized by rapid progression and a poor prognosis. Fistula formation caused by intestinal lymphoma is extremely uncommon, and no previous reports have described MEITL presenting with a jejunocolic fistula. An 83-year-old woman presented with a 20-kg weight loss and generalized fatigue over the preceding year. Laboratory tests revealed hypoalbuminemia and elevated inflammatory markers. Computed tomography demonstrated wall thickening of the jejunum and descending colon, suggesting possible continuity between the two segments. Colonoscopy revealed a circumferential ulcerative lesion at the splenic flexure, and proximal to this lesion, another lumen extending in a direction different from the colonic lumen was observed. Biopsy confirmed a diagnosis of MEITL. Positron emission tomography-computed tomography (PET-CT) showed abnormal FDG uptake from the jejunum to the transverse colon, and the disease was classified as Lugano Stage II. Due to tumor location and the patient's poor general condition, both surgery and chemotherapy were considered infeasible, and best supportive care was chosen. The patient died on hospital Day 33. Jejunocolic fistula caused by MEITL is exceptionally rare. To our knowledge, this is the first reported case in which the fistulous opening was directly visualized endoscopically and a histopathological diagnosis was established by biopsy during life. This case highlights that, in patients with marked weight loss and hypoalbuminemia, gastrointestinal fistula formation should raise suspicion for malignant lymphoma, including MEITL, and that careful endoscopic examination and biopsy may contribute to early diagnosis.