Colorectal Cancer Premalignant Lesions

Synonyms

Adenomas; Adenomatous polyps; Microadenomas

Definition

Colorectal cancer premalignant lesions are focal lesions which precede cancer development. There are different entities: adenoma is the only one for which the available scientific evidence of its premalignant nature is more convincing.

Colorectal adenomas are polypoid, flat, or depressed lumps of epithelial origin, which can be found throughout the large bowel, whose main histological feature is dysplasia. They may be single or multiple, rarely hundreds or even thousands, as in patients with familial adenomatous polyposis (FAP). Adenomas, if left untreated, grow and finally may become malignant. However, only a fraction of colorectal adenomas acquire malignant features, and sometimes may also regress. Polypoid adenomas are the most frequent and can be sessile (with a large base) or pedunculated (with a stalk attached by a narrow base on the colorectal mucosal surface).

Other kinds of colorectal lesions may be premalignant;...