Proximal sessile serrated lesion without dysplasia. The purpose of our study was to determine the prevalence of dysplasia in patients with pSSLs (pSSLdys) and describe the associations of these lesions. In a retrospective study, pSSLs was associated with smoking and tended to be larger compared to distal SSLs. The prevalence of dysplasia in such lesions has been reported to be 8%–27%. While extensive literature on SSLs exists, there has been little focus on the characteristics of proximal SSLs (pSSLs). Recognising the significance of the serrated pathway, other measures have been proposed as a quality indicators to complement ADR, such as serrated polyp detection rate (SPDR) and proximal SPDR. Adenoma detection rate (ADR) has been firmly established as a quality indicator for colonoscopy performance. The window of opportunity to detect and resect SSL with dysplasia is small, leading to efforts to improve colonoscopy quality. Among patients with interval CRCs, there is a disproportionately higher contribution from lesions arising from the serrated pathway. Studies have shown that screening colonoscopy reduces the incidence for distal but not proximal CRC. ĭue to the slow sojourn from dysplasia to malignancy, colonoscopy with polypectomy has a central role in the battle against CRC. Patients with SSLs with dysplasia have higher odds of developing CRC when compared to patients with non-dysplastic SSLs. This is in contrast with adenoma-carcinoma sequence, which is predominantly driven by activation in K-ras proto-oncogene, loss of p53 and APC. Loss of MLH1/PMS2 is believed to initiate the transition to dysplastic change. Four patterns of dysplasia have been described, with two types having high frequencies of MLH1 expression loss, a tumour suppressor gene. The presence of dysplasia in SSLs range from 2%–30%. The emergence of cytological dysplasia within SSLs is a critical step in carcinogenesis, as its appearance often initiates a rapid progression to malignancy. Most SSLs have somatic BRAF (V600E) mutation with CIMP-positive phenotype. Typically, NICE-2 lesions predict a histology of tubular adenoma with dysplasia. On NBI, the lesion appears brown, with visible brown vessels and tubular branched white structures, findings consistent with type 2 neoplasm on narrow-band imaging international colorectal endoscopic (NICE) classification. Paris Type Is lesion with a nodular surface predictive of cytological dysplasia. White light (A) and narrow band imaging (NBI) (B) views of a proximal sessile serrated lesion with dysplasia. Proximal sessile serrated lesion with dysplasia. regarded serrated lesions as being clinically significant if they are proximal to the splenic flexure or larger than 10 mm. Serrated lesions which harbour dysplasia or are larger than 10 mm have been reported to carry a higher risk of progression to CRC. Among SSLs, proximal polyps are considered to have higher malignant potential. ![]() Ĭompared to adenomatous lesions, SSLs are morphologically flatter and tend towards proximal distribution ( Figs. These are molecular features that are commonly seen in sessile serrated lesions (SSLs). Proximal CRCs tend to occur in older persons, women and are associated with microsatellite instability (MSI) high, CpG island methylation phenotype (CIMP) positive and BRAF mutations. Proximal CRCs account for one third to half of all CRCs and are considered biologically distinct from distal CRC. Epidemiological studies estimate that the serrated pathway contributes up to 30% of CRCs. ![]() The adenoma-carcinoma sequence was once considered to be the only way by which CRCs develop but studies in recent years have shown that serrated lesions are also precursors to CRCs. There are two well established molecular pathways CRCs arise from. Colorectal carcinoma (CRC) is a leading cause of cancer related morbidity and mortality.
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