| Abstract: | Abstract: Over the last two years, a total colonoscopy was performed on 3,006 patients and 232 colorectal carcinomas were detected in these patients. Seventy one (30.6%) of the carcinomas were found to be early cancers. Eighteen (25.4%) of these 71 early cancers were minute (>5 mm) colorectal carcinomas of the flat or depressed type and they were resected endoscopically. More than half of them were accompanied by colonic polyps. Among the characteristic endoscopic features of flat and depressed early colorectal carcinomas are redness, fine granularity and defects of the innominate groove on the lesional surface. Another important finding is whitish annular mucosa surrounding the lesion. The gross appearance of these lesions was depression (3 lesions), depression with a marginal elevation (11 lesions), or flat (4 lesions). On histological examination, all the lesions were found to be well–differentiated intramucosal adenocarcinoma. It appears that depressed lesions with or without marginal elevation have a tendency to horizontal and vertical invasion, respectively. Moreover, it is thought that flat lesions are very early cancers that might later develop into depressed lesions with or without marginal elevation, or flat elevated lesions. |
