| [ Summary ] |
From the general concept that colorectal adenocarcinomas invade through the muscularis mucosa into the submucosa, the level of submucosal invasion is histopathologically defined as the degree of invasion below the muscularis mucosa. However, it is not rare to experience difficulties in recognizing muscularis mucosa in the invasive area of colorectal adenocarcinomas, because of the remodelling of the histologic architecture associated with invasion. Therefore, the muscularis mucosa is not always a definite landmark for determining the level of submucosal invasion of colorectal adenocarcinomas. From this point of view, the level of submucosal invasion of colorectal adenocarcinomas may be determined according to the status of the muscularis mucosa (carcinomas for which the muscularis mucosa can be a definite landmark of submucosal invasion, and those for which the muscularis mucosa is not definite). In the latter cases, the level of submucosal invasion alone is not a significant factor for evaluating the possibility of metastasis and/or recurrence, or in determining the necessity of surgical procedures after endoscopic resection, because they are regarded as basically having a metastatic potential. Although there has been controversy over how the level of submucosal invasion of pedunclated colorectal adenocarcinomas is determined, there should also be revaluations made, according to the status of the muscularis mucosa. |