English: Very high magnification micrograph of a sessile serrated adenoma, abbreviated SSA, from the cecum removed during a colonoscopy. H&E stain.

SSAs are characterized by:

• basal dilation of the crypts,
• basal crypt serration,
• crypts that run horizontal to the basement membrane (horizontal crypts), and
• crypt branching.

Unlike traditional colonic adenomas (e.g. tubular adenoma, villous adenoma), they do not typically have nuclear changes (nuclear hyperchromatism, nuclear crowding, elliptical/cigar-shaped nuclei).

SSAs are considered pre-malignant lesions, i.e. precursors to cancer, and tend to be found in the right colon.

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