Colonic polyp. Colonoscope (endoscope) view of a benign (non-cancerous) polyp in a 67 year-old man's colon (large intestine). This is a tubulovillous adenoma, a tumour arising from the epithelial tissue lining an organ. Unlike more common polyps, which are attached on a stalk, this type (tubulovillous) forms in a tube shape. If the polyp causes discomfort, or it is suspected that it may turn cancerous, it is removed surgically. In this case, after removal the polyp was found to contain high-grade dysplasia (HGD), the medical term for cell abnormality, which could indicate that the polyp was becoming cancerous.