Colorectal polyp. Coloured 3D computed tomography (CT) scan showing a small polyp (round, centre) at the entrance to the transverse colon of a 44-year-old female patient. Polyps are benign (non-cancerous) growths that arise from mucous membranes. Although benign, polyps are generally removed surgically as their growth may obstruct the passage of food and some polyps may turn cancerous over time.