Evaluation of endoscopic and histopathological features of serrated adenoma of the colon

The aim of this study was to reveal the clinical features of serrated colonic adenoma by investigating its endoscopic features using a magnifying videoscope.

68 colorectal serrated adenomas presented for colonoscopic examination were included in this study. A magnifying videoscope with a zoom ranging from x 1 to x 100 magnification was employed to observe the pit patterns of colonic lesions, and 39 of the serrated adenoma specimens were evaluated using this. Some pit patterns appeared as elongated oval and stellar-like orifices of the crypts; we termed these type which was detected III(SA) patterns. Other pit patterns showed a flower petal-like or pineal form, and this was termed a type IV(SA) pit pattern.

In the entire sample of serrated adenomas, 53 were of the protruded type, and 15 were superficial, for a protruded/superficial ratio of 3.5 : 1. The protruded type of serrated adenoma predominated in the distal portion. The superficial type was preferentially located in the proximal portion of the colon (P < 0.0001). Among the 13 superficial types in which the magnifying videoscope was used, all 13 showed the type III(SA) basic pit pattern. In these serrated adenomas of the superficial type, an additional IV(SA) pit pattern was found in 23.1% (3/13), which was detected in 53.8% (14/26) in the protruded type. Small serrated adenomas measuring less than 10 mm in diameter were preferentially mild to moderate atypia (odd's ratio = 15.9, P = 0.0216).

The pit pattern may prove useful for the endoscopic diagnosis of serrated adenoma. Furthermore, endoscopic treatment is indicated for serrated adenoma; in particular those of 10 mm or more in diameter should be treated because of the possibility of high-grade glandular intraepithelial neoplasia.