Sessile serrated lesion

A sessile serrated lesion (SSL) is a premalignant flat (or sessile) lesion of the colon, predominantly seen in the cecum and ascending colon. SSLs are thought to lead to colorectal cancer through the (alternate) serrated pathway. This differs from most colorectal cancer, which arises from mutations starting with inactivation of the APC gene. Multiple SSLs may be part of the serrated polyposis syndrome. SSLs are generally asymptomatic. They are typically identified on a colonoscopy and excised for a definitive diagnosis and treatment. serrated polyposis syndrome The serrated polyposis syndrome (SPS) is a relatively rare condition characterized by multiple and/or large serrated polyps of the colon. Serrated polyps include SSLs, hyperplastic polyps, and traditional serrated adenomas. Diagnosis of this disease is made by the fulfillment of any of the World Health Organization’s (WHO) clinical criteria. SSLs are diagnosed by their microscopic appearance; histomorphologically, they are characterized by (1) basal dilation of the crypts, (2) basal crypt serration, (3) crypts that run horizontal to the basement membrane (horizontal crypts), and (4) crypt branching. The most common of these features is basal dilation of the crypts. Unlike conventional colonic adenomas (e.g. tubular adenoma, villous adenoma), they do not (typically) have nuclear changes (nuclear hyperchromatism, nuclear crowding, elliptical/cigar-shaped nuclei). Image:Sessile serrated adenoma 3 low mag.jpg|Low magnification [[micrograph]] of an SSL. Image:Sessile serrated adenoma 3 intermed mag.jpg|Intermediate magnification micrograph of an SSL. Image:Sessile serrated adenoma 2 high mag.jpg|High magnification micrograph of a SSL showing crypt branching. Complete removal of a SSL is considered curative. Several SSLs confer a higher risk of subsequently finding colorectal cancer and warrant more frequent surveillance. The surveillance guidelines are the same as for other colonic adenomas.