| [ Summary ] |
In this article, the history and present status of the pathology of depressed type (0-IIc) colorectal cancer have been summarized. The first case of this type of cancer was reported by Kariya et al., in 1977 and 0-IIc was detected based on barium enema in the patients with familial adenomatous polyposis. Histologically, neoplastic crypts exhibited a straight shape with prominent nuclear atypia, indicating a well-differentiated tubular adenocarcinoma, and the histology was considered in the majority of 0-IIc cases. Meanwhile, signet-ring cell carcinoma or poorly differentiated adenocarcinoma was also known to exhibit 0-IIc type histology even if its frequency is low. Subsequent increase in the number of 0-Ⅱc cases revealed that 0-IIc tends to invade the submucosal layer frequently, although the size is relatively small. Generally, 0-IIc is regarded as a representative morphology of de novo colorectal cancer; however, there are a few cases of 0-IIc derived from depressed adenoma or protruded type tumor. Inter-observer reproducibility among pathologists remains poor and has not been overcome as yet. Recently, 0-IIc has been detected and subsequently its cases were reported in several countries other than Japan. |