Current progress on the endoscopic features of colorectal sessile serrated lesions

Abstract

Along with the discovery and refinement of serrated pathways, the World Health Organization amended the classification of digestive system tumors in 2019, recommending the renaming of sessile serrated adenomas/polyps to sessile serrated lesions (SSLs). Given the particularity of the endoscopic appearance of SSLs, it could easily be overlooked and missed in colonoscopy screening, which is crucial for the occurrence of interval colorectal cancer. Existing literature has found that adequate bowel preparation, reasonable withdrawal time, and awareness of colorectal SSLs have improved the quality and accuracy of detection. More particularly, with the continuous advancement and development of endoscopy technology, equipment, and accessories, a potent auxiliary tool is provided for accurate observation and immediate diagnosis of SSLs. High-definition white light endoscopy, chromoendoscopy, and magnifying endoscopy have distinct roles in the detection of colorectal SSLs and are valuable in identifying the size, shape, character, risk degree, and potential malignant tendency. This article delves into the relevant factors influencing the detection rate of colorectal SSLs, reviews its characteristics under various endoscopic techniques, and expects to attract the attention of colonoscopists.

The histologic features, molecular features, detection and management of serrated polyps: a review

“…A fundamental distinction from HPs is that the entire saphenous fossa demonstrates serration and grows horizontally along the mucosal muscular layer, specifically within the third of the crypt basal expansion. Dysplasia is not observed in uncomplicated SSLs, however, SSLs with areas of conventional (tubular or tubulovillous) adenoma-like dysplasia may indicate progression towards carcinoma ( 9 , 20 , 22 , 28 ).…”

“…This results in the formation of small papillae that extend into the lumen of the saphenous fossa, thereby giving the luminal surface a serrated appearance ( Figure 2A ). The diagnosis of HPs requires the presence of a distinctive serrated shape in the epithelium, while lacking the histological criteria associated with SSLs ( 13 , 22 ).…”

“…The surrounding glands adjacent to the SSL-Ds exhibit villous structures that are longer and more densely packed, displaying complex branching, sieve-shaped crypts, and increased or decreased serration compared to those in SSLs. Furthermore, the utilization of immunohistochemical analysis for MLH1 is crucial in the determination of the presence of clinically significant dysplasia within SSLs ( 9 , 20 , 22 ).…”

“…NBI (Nice type 1) can reveal varicose microvascular vessels running throughout the deep mucosal layer ( Figure 3C ). The diagnostic characteristics of SSLs include inconspicuous borders, cloud-like surfaces, dark spots, and varicose microvascular vessels ( 9 , 12 , 13 , 22 ).…”

“…In contrast, SSL-Ds are frequently characterized by a pedicled, bimodal appearance, central depression, and reddish color. When observed under white light endoscopy, most SSL-Ds are likely to display either large or small nodules on the surface, while chromoendoscopy reveals Kudo type III or Kudo type IV patterns ( 12 , 22 ).…”