Carcinoma in situ in nonpolypoid mucosa of the large intestine. Report of a case with significance in strategies for early detection.

A case of carcinoma in situ of the flat, nonpolypoid mucosa of the large intestine in a 32-year-old man is reported. This case is of unusual importance because it was detected by endoscopy and was effectively managed; it sheds further light into the histogenesis of large intestinal carcinomas; and it points to alternate strategies for early detection and prevention of large intestinal carcinomas.