Colon polyp. Light micrograph of a section through part of a tubulovillous adenoma of the mucosa of the large bowel (colon). In this polyp the intestinal glands have multiplied in number to produce complex, disorganised branchings covered with mucous-secreting goblet cells. Large bowel polyps are very common and although initially benign, progression to malignancy is a concern if undetected and untreated. This is because such adenomas have variable proportions of dysplastic cells capable of transformation into invasive cancerous cells or adenocarcinoma. The causes of polyp development and progression to cancer are multifactorial and include diet, exposure to carcinogens, chronic inflammatory conditions and genetic predisposition. Magnification: x22, when