Cancerous polyps of the colon, gross specimen. These are adenocarcinomas, a type of cancer arising from glandular epithelial tissue. Polyps are abnormal growths of tissue (tumours) projecting from a mucous membrane. The ones seen here are red upon a slender stalk and are hence known as pedunculated. These polyps are cancerous. Most polyps are non-malignant but when detected are removed as they present a risk for transition to invasive cancer of the bowel, as is seen here.