Sessile serrated adenoma
|Sessile serrated adenoma|
|Classification and external resources|
In gastroenterology, a sessile serrated adenoma (abbreviated SSA), also known as sessile serrated polyp (abbreviated SSP), is a premalignant flat (or sessile) lesion of the colon, predominantly seen in the cecum and ascending colon.
SSAs 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 SSAs may be part of the serrated polyposis syndrome.
SSAs, generally, are asymptomatic. They are typically identified on a colonoscopy and excised for a definitive diagnosis and treatment.
SSAs 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.
Serrated polyposis syndrome
The serrated polyposis syndrome (SPS) is a relatively rare condition characterized by multiple and/or large serrated polyps of the colon. Diagnosis of this disease is made by the fulfillment of any of the World Health Organization’s (WHO) clinical criteria.
Complete removal of a SSA is considered curative.
Several SSAs confer a higher risk of subsequently finding colorectal cancer and warrant more frequently screening. The screening guidelines are the same, as for other colonic adenomas. The screening interval is dependent on (1) the number of adenomas, (2) their size and, (3) whether high-grade microscopic features are present.
Low magnification micrograph of a SSA.
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