| [ Summary ] |
Type IIc intramucosal lesions had typically been diagnosed as carcinoma due to their peculiar macroscopic morphology and growth pattern. However, there has been a consensus among pathologists that type IIc is not necessarily carcinoma. According to the author's pathological diagnostic criteria, most of such lesions were diagnosed as adenomas. On the other hand, based on the examination of pT1 carcinoma with residual intramucosal carcinoma, it is considered that type IIc intramucosal carcinoma develops de novo as a high-grade carcinoma and invades the submucosa with a smaller size (around 10 mm) than other types of carcinomas. While colorectal cancer derived from type IIc intramucosal carcinoma accounted for approximately 8.4 %, considering the pathological characteristics of pT1 carcinoma without residual intramucosal carcinoma, more colorectal carcinomas are derived from type IIc intramucosal carcinoma. To clarify the pathological significance of type IIc, pathological analysis of pT1 carcinoma without residual intramucosal carcinoma is an issue for the future. |