Su1703 High Definition Colonoscopy With I-SCAN and Digital Chromoendoscopy in the Pit Pattern Analysis: a Single Center Experience

Abstract

Su1702 Diagnostic Characteristics of Depressed Type Colorectal Neoplasms Examined With Magnifying Chromo-Endoscopy and Endocytoscopy Shin-Ei Kudo*, Kazuki Kato, Katsuro Ichimasa, Hideyuki Miyachi, Yuta Kouyama, Shingo Matsudaira, Hiromasa Oikawa, Tomokazu Hisayuki, Yui J. Kimura, Yuichi Mori, Masashi Misawa, Toyoki Kudo, Kenta Kodama, Kunihiko Wakamura, Takemasa Hayashi, Atsushi Katagiri, Eiji Hidaka, Fumio Ishida Showa University Northern Yokohama Hospital, Yokohama, Japan Introduction & Aim: Colorectal carcinomas are generally recognized to develop from sessile-type “polyps”. This “adenoma-carcinoma sequence” theory has been in the mainstream of development of colorectal cancers. But recently the existence of many depressed-type cancers has been revealed, which are considered to emerge directly from normal epithelium, not through the adenomatous stage. This theory is called “de novo” pathway. Now, it is possible to estimate the histology of colorectal lesions using magnifying chromo-endoscopy (pit pattern classification) and endocytoscopy (EC) which can observe not only the structural atypia but also the cellular atypia in living colorectal lesions. The aim is to clarify the diagnostic characteristics of depressed-type colorectal neoplasms, demonstrating the validity of pit pattern diagnosis and EC classification. Methods: A total of 22903 colorectal neoplasms excluding advanced carcinomas were resected endoscopically or surgically in our unit from April 2001 to June 2014. Of these, 14522 lesions were low-grade dysplasia, 4956 were high-grade dysplasia and 968 were submucosally invasive (T1) carcinomas. According to morphological/development classification, they were divided into 3 types: depressed, flat and sessile type. We investigated the rate of T1 carcinomas and the characteristics of depressed-type neoplasms concerning pit pattern and EC classification. Results: The rate of T1 carcinomas in depressed-type lesions reached to 63.7 %, meanwhile that in flat-type and sessile-type lesions was 4.1 % and 3.1 %, respectively. Within less than 5mm in diameter, that was 10.2 %, 0 % and 0.06 %, respectively. Most (88.3 % and 91.2 %) of the flat-type and sessile-type lesions showed type IIIL or IV pit pattern corresponding to adenomas, whereas 94.5 % of the depressed-type lesions were characterized by type IIIs, VI or VN pit pattern corresponding to carcinomas. As for endocytoscopy, most of the flatand sessile-type lesions showed EC2 corresponding to adenomas. In contrast, the depressed-type lesions were observed as EC3a (23.5 %) and EC3b (74.1 %) corresponding to invasive carcinomas. Conclusion: This study revealed the diagnostic characteristics of depressed-type lesions. They show typically type IIIs, VI or VN pit patterns in magnifying endoscopy and type EC3a or EC3b in endocytoscopy. These lesions tend to invade the submucosal layer even when they are small. Therefore, more careful endoscopic diagnosis of ‘whether the lesion is depressed type or not’ would be important.