Colon, Sessile serrated adenoma

Sessile serrated adenomas have an incidence of 1-10% of all colorectal polyps. They are usually right sided, and the median age of affected patients is 61-62 years. Molecular characteristics include CpG island methylation phenotype and BRAF oncogene activating mutations.

Microscopically, they are characterized by serration (resulting from in-folding of crypt epithelium), dilatation and exaggerated serration extending down to crypt base, branching or lateral growth of crypt along muscularis mucosae, and L-boot shaped crypt bases.