Pseudocarcinomatous invasion in adenomas of the colon and rectum.

Of 182 polyps retrieved from 100 patients who underwent colonoscopic polypectomies, 160 were adenomas; of these, 16 contained epithelial inclusions within the stalk. The importance of recognizing this lesion lies in the fact that it mimics invasive cancer. From histologic study, criteria are proposed for differentiating the pseudocarcinomatous lesion from invasive cancer. The differentiation from colitis cystica profunda is also discussed.