A case of atypical rectal tumor in a 55-years-old man?

A 55-year-old patient consulted a gastroenterologist in January 2023 because of recent-onset urgent diarrhea, without rectal bleeding or hematochezia. The patient has a history of diffuse large cell lymphoma with lymph node, bone and suspected small bowel involvement on 18F-FDG-PET/CT imaging, for which a differential diagnosis with a neuroendocrine tumor could not be formally made. He had no other medical or surgical history, and was a former smoker. Physical, digital rectal examinations and laboratory studies were unremarkable. A colonoscopy was performed and revealed a poly-poid soft formation of non-adenomatous appearance, measuring 30 mm x 30 mm.