Colorectal Cases

Overall Comment

Laterally spreading tumors (LSTs) were originally classified into four subtypes by Shin-ei Kudo et al., including LST-G and LST-NG. LST-G is subclassified into homogeneous (LST-G-H) and nodular mixed types (LST-G-M), and LST-NG is divided into flat elevated (LST-NG-F) and pseudo-depressed types (LST-NG-PD).

LST-G types tend to have less submucosal carcinoma, irrespective of the size of the lesion. However, the LST-NG types tend to be more aggressive, with a higher incidence of advanced carcinoma, especially the pseudo-depressed type.

Different classifications help predict the risk of submucosal invasion, such as the NICE classification and the JNET classification. Its subclass JNET2a is mostly comprised of intraepithelial lesions; JNET3 is composed mainly of deep submucosal invasive lesions; and JNET2b can be found in both intramucosal and submucosal invasive lesions.

When a part of the polyp is hidden behind a fold or clamshell wrapped around a fold, endoscopists encounter challenges in visualizing the entire surface area of the polyp. Underwater observation could help solve this issue.

This is a LST-NG-PD with a 16-mm diameter. The lesion has a red O-ring with a depressed area about 14mm in diameter. In “air” endoscopy and underwater endoscopy, the lesion has a “non-extension” or “sclerosis of the wall” sign. Observing in the “near focus” magnifying endoscopy, some areas had JNET type 2b, suggesting that this is either an intramucosal cancer lesion or a cancer lesion with submucosal invasion.

We resect the lesion by FTRD (Full-Thickness Resection Device) due to failure to resect the lesion by ESD.