Endoscopic features and management of diminutive colorectal submucosal invasive carcinoma

Background and Aim The vast majority of diminutive (similar to 5 mm) colorectal tumors consist of a very low prevalence of advanced neoplasia, and a predict-resect-and-discard policy has been proposed recently in Western countries. The histology of some diminutive colorectal tumors reveals carcinoma, not adenoma, although the frequency is relatively low. Clarifying the endoscopic features of diminutive submucosal invasive colorectal carcinoma (CRC) during colonoscopy is important for managing diminutive lesions. Methods A total of 111 cases of submucosal invasive CRC <= 10 mm were analyzed. The incidence of submucosal invasion in early CRC per gross type, size, location, pit pattern diagnosis, and rate of lymph node (LN) metastasis was evaluated. Results In diminutive tumors, the overall submucosal invasion rate in early CRC was 9.6%; however, depressed tumors had a significantly higher frequency of submucosal invasion than protruded or flat elevated tumors. There were no significant differences in the distribution of submucosal invasive CRC between the diminutive tumors and those that were 6-10 mm. The pit pattern diagnosis of diminutive submucosal invasive CRC was type V-I pit pattern in all cases. Each case of submucosal invasive CRC was completely resected by en bloc endoscopic resection, and there were no cases of LN metastasis. Conclusion Diminutive tumors with depression have a high frequency of submucosal invasive CRC and an initial indication for endoscopic resection.