Small primary de novo adenocarcinoma of the colon with mesenteric lymphatic metastasis.

It is felt that the majority of colorectal carcinomas develop by malignant degeneration of previously benign adenomatous polyps. A small primary colon carcinoma, thought to have developed de novo directly from the colonic mucosa without the usual polyp-cancer sequence, is reported. This small nonulcerated lesion did not have the gross endoscopic appearance of a carcinoma and was associated with lymphatic metastasis. The need to include fiber-optic colonoscopy as part of the routine preoperative work-up and postoperative follow-up to rule out synchronous and metachronous lesions not detected by barium contrast x-ray studies is stressed.