| [ Summary ] |
The recognition of a new concept concerning colonic lesions and the advent of the video endoscope have shown that the categorization colonic tumors should not only include the polyp type but also endophytic growth tumors. These include depressed type lesions, and laterally spreading tumors (LST). The difficulty in endoscopic diagnosis of these two types -- depressed type and LST -- depends mainly on their gross configuration. They are usually detected endoscopically by a faint redness or roughness on their surface. The majority of LSTs were classified as adenomas or pTis carcinomas histopathologically, even though tumor sizes were over 20 mm in diameter. Previous reports indicate that almost all LSTs are treatable with endoscopic mucosal resection (EMR). Furthermore, these flat lesions are frequently recognized not only in Japan, but in other countries as well. Since 1996, many papers have been published on this subject and LST has become a key word for endoscopic research in worldwide medical literature. Japanese colonoscopists should publish more papers concerned with LST. |