Advances in Endoscopy

XB Serrated colon polyps are a group of heterogeneous lesions characterized histologically by glandular serration (ie, a saw-toothed folding of colonic crypt epithelium). The World Health Organization has classified serrated lesions into 3 general categories (Table). Historically, serrated polyps were called hyperplastic polyps (HPs) and were thought to have no malignant potential. However, recent data have established that several distinct subtypes of serrated polyps are the precursors of a group of colorectal cancers (CRCs) that exhibit hypermethylation and arise primarily in the proximal colon, the so-called serrated neoplasia pathway, characterized by BRAF mutations and a CpG island methylator phenotype (CIMP). It has been estimated that serrated polyps might be the precursors for approximately 15% to 20% of sporadic CRCs, particularly in the proximal colon, and most CRCs arise through the conventional adenoma pathway characterized by chromosomal instability. Many studies have shown that benign serrated lesions and CIMP-high CRCs share molecular features. In fact, it has been suggested that HPs lead to sessile serrated adenomas/polyps (SSA/Ps) without dysplasia and then dysplasia develops and finally leads to cancer. Moreover, some interval proximal cancers have been attributed to the serrated pathway, emphasizing the need to detect serrated polyps during endoscopic examinations. Therefore, endoscopists should familiarize themselves with detection of these lesions, particularly those that are located in the proximal colon. G&H How common are the different types of serrated polyps?