Monomorphic Epitheliotropic Intestinal T-Cell Lymphoma in the Ileum with Successful Preoperative Endoscopic Evaluation

A 80-year-old man with the history of operations for gastric cancer and adhesive ileus developed abdominal pain. Positron emission computed tomography (CT) showed prominent wall thickening in the ileum with a maximal standardized uptake value of 12.1. Prior CT to diagnose adhesive ileus just taken only 4 months before did not show any masses in the abdomen. Single-balloon enteroscopy via colon showed a protruding mass at approximately 40–50 cm proximal point from the ileum end. Pathological examination of the biopsied specimen showed diffuse infiltration of medium- to large-sized atypical lymphocytes. Immunohistochemistry analysis showed that the atypical cells were positive for CD3 and CD56 and negative for CD8 and CD20. MIB-1 labeling index was extremely high as 80%. Under the diagnosis of intestinal T-cell lymphoma, the patient underwent tumorectomy, leading to the diagnosis of monomorphic epitheliotropic intestinal T-cell lymphoma (MEITL) after the negativity confirmation of Epstein-Barr virus-encoded mRNAs. The patient recovered with manageable complication and is going to receive chemotherapy. This is the first case of MEITL with extremely rapid progression in the distal ileum to be observed and diagnosed with single-balloon enteroscopy.