A polyp is a small accumulation of tissue that grows along the inside of the colon or rectum. Colon and rectal surgeons classify polyps into one of two types – hyperplastic polyps and adenomatous polyps. Hyperplastic polyps are benign and usually do not become cancerous, though the risk is still present. Adenomatous polyps, on the other hand, are much more likely to become malignant and occur in larger numbers. All colon and rectal polyps can grow for years, causing little more than some minor rectal bleeding. As they grow bigger, however, they may become malignant or lead to cramping and abdominal pain. Large benign polyps can secrete large amounts of mucous causing loose, frequent stools.