Polyps (eFigure 15–82) are discrete mass lesions that protrude into the intestinal lumen. Although most commonly sporadic, they may be inherited as part of a familial polyposis syndrome. Polyps may be divided into four major pathologic groups: mucosal adenomatous polyps (tubular, tubulovillous, and villous) (eFigure 15–83), mucosal serrated polyps (hyperplastic, sessile serrated polyps, and traditional serrated adenoma), mucosal nonneoplastic polyps (juvenile polyps, hamartomas, inflammatory polyps), and submucosal lesions (lipomas, lymphoid aggregates, carcinoids, pneumatosis cystoides intestinalis). Of polyps removed at colonoscopy, over 70% are adenomatous; most of the remainder are serrated. Adenomatous polyps and serrated polyps have significant clinical implications and will be considered further below.
Pedunculated polyp. If a polyp is attached to the surface by a narrow, elongated stalk, it is said to be pedunculated. On histopathology, this polyp was a tubulovillous adenoma. (Used, with permission, from Michelle Nazareth, MD.)
Tubulovillous adenoma. Colonoscopy shows a large 2 cm colonic polyp. The long stalk indicates that this is a pedunculated polyp, as opposed to a sessile (or flat) polyp. After its removal, pathology revealed this polyp to be a tubulovillous adenoma. (Used, with permission, from Robert Osterhoff, MD.)