This 43 year old woman with hematochezia was referred for colonoscopy. In the rectal vault a large villous appearing lesion is seen carpeting a broad area. The central nodular region of the lesion is depressed and bleeding. This area is worrisome for malignant degeneration. On retroflexed view, the lesion is seen to approach within 2 cm of the dentate line. Biopsies are taken. Low power examination of the tumor shows prominent villi of a villous adenoma. Closer examination reveals the villi are lined by crowded epithelial cells with enlarged pencil shaped nuclei that are hyperchromatic and stratify towards the surface. Given the size of the lesion and the region of central umbilication, a clean lift for EMR is not recommended.
Peter B. Kelsey, M.D., Harvard Medical School, Massachusetts General Hospital