Sessile serrated lesions: Clinicopathological characteristics, endoscopic diagnosis, and management

Abstract

The 2019 World Health Organization (WHO) Classification of Tumours of the Digestive System (5th edition) introduced the term "sessile serrated lesion" (SSL) to replace the term "sessile serrated adenoma/polyp" (SSA/P). SSLs are early precursor lesions in the serrated neoplasia pathway that result in colorectal carcinomas with BRAF mutations, methylation for DNA repair genes, a CpG island methylator phenotype, and high levels of microsatellite instability. Some of these lesions can rapidly become dysplastic or invasive carcinomas that exhibit high lymphatic invasion and lymph node metastasis potential. The 2019 WHO classification noted that dysplasia arising in an SSL most likely is an advanced polyp, regardless of the morphologic grade of the dysplasia. Detecting SSLs with or without dysplasia is critical; however, detection of SSLs is challenging, and their identification by endoscopists and pathologists is inconsistent. Furthermore, indications for their endoscopic treatment have not been established. Moreover, SSLs are considered to contribute to the development of postcolonoscopy colorectal cancers. Herein, the clinicopathological and endoscopic characteristics of SSLs, including features determined using white light and image-enhanced endoscopy, therapeutic indications, therapeutic methods, and surveillance are reviewed based on the literature. This information may lead to more intensive research to improve detection, diagnosis, and rates of complete resection of these lesions and reduce post-colonoscopy colorectal cancer rates.

Colorectal polyp outcomes after participation in the seAFOod polyp prevention trial: Evidence of rebound elevated colorectal polyp risk after short‐term aspirin use

“…In general, serrated‐hyperplastic polyps detected during surveillance were larger than adenomatous polyps. This observation might be explained by a faster growth rate and/or higher colonoscopy miss rate for serrated lesions, 13 which could also underlie the prominent relationship between previous aspirin or EPA treatment and larger serrated‐hyperplastic polyps. There was an excess of proximal colorectal polyps during second and subsequent rounds of surveillance of this ‘high‐risk’ cohort of screened individuals, which is consistent with a left‐to‐right shift reported in other surveillance colonoscopy cohort studies 14 …”

Colon polyps: updates in classification and management

“…The most recent 2019 WHO classification categorizes serrated colon polyps as hyperplastic polyp, sessile serrated lesion (SSL) and traditional serrated adenoma (TSA) [9,10]. The term SSL replaced the 2003 terminology 'sessile serrated adenoma' which had been the general terminology to describe such precancerous lesions arising from the serrated polyp pathway; however, its wide adoption and replacement of the older terminology continues to remain controversial [11].…”

“…Therefore, it has been recommended that retroflexion in the right colon or a second forward view reexamination can improve the quality of detection of these colon polyps. Currently, it is estimated that SSL are still underdiagnosed by pathologists who have not updated to the most recent WHO pathology classification guidelines [10]. If there is suspicion for an SSL in the right colon, the clinician can consult with the case pathologist to determine the likelihood of SSL pathology to make correct surveillance exam recommendations.…”

Therapeutic effects of natural polyphenols on colorectal adenomas: Focus on preclinical studies (Review)

“…By contrast, ~10-20% of CRC have a different pathway-serrated neoplasia pathway. The mechanism of SSLs mainly involves BRAF mutation, KRAS mutation, CpG island methylation phenotype and microsatellite instability ( 7 ). SSLs occur in the proximal colon, particularly in the cecum and ascending colon, and grow significantly faster than tubular adenomas ( 8 ).…”