Incidence and distribution of adenomatous polyps of the colon and rectum based on 1,000 autopsy examinations

DUE tO differences in method, thoroughness of examination and variations in interpretation of patholgg!c changes, considerable discrepancies exist in the reported incidence of adenomatous polyps of the colon and rectum. To more accurately determine this incidence, the colons of 1,000, and the rectums of 120, adults undergoing autopsy were examined by the authors. The location, size and gross characteristics of all grossly recognizable lesions were tabulated. All lesions were removed and cross sectioned for microscopic study. ' The term "polyp" applies to a tumor of the mucous membrane. Originally applied only to pedunculated tumors, now it is used to designate sessile tumors as well. A lesion which appears grossly as a polyp may be histologically an adenoma, fibroma, carcinoid, lipoma, pseudopolyp, and so forth (Fig. la-f). While generally there is uniform agreement about the pathology of large polyps, there is considerable variation in the interpretation of microscopic findings of polyps that are small. Small polyps, usually 1 to 3 mm. in diameter, when studied microscopically, are of three types; namely, mucosal, hyperplastic and adenomatous. To differentiate the mucosal and hyperplastic types from normal mucosa, it is necessary that the specimen be studied in cross section ~ (,lg. 2a and b). The mucosal polyp is an elevation o~ -the mucosa with some apparent edema or thickening of the submucosa. There are no changes in the glands or the underlying