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<unk>  adenoma 3 low mag.Low magnification micrograph of an SSL. Image:Sessile<unk>  adenoma 3 intermed mag.Intermediate magnification micrograph of an SSL. Image:Sessile<unk>  adenoma 2 high mag.High magnification micrograph of a SSL showing crypt branching.
Sessile serrated lesion
Aberrant crypt foci
Hyperplastic polyp
Squamous intraepithelial lesion
Traditional serrated adenoma
Cameron lesions
Inflammatory fibroid polyp
Intraepithelial neoplasia