English: Micrograph of a sessile serrated adenoma (SSA) from the right colon removed during a colonoscopy. H&E stain.

The specimen consists primarily of colonic type epithelium; however, there is also a small amount of lamina propria and muscularis mucosae.

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. The above mentioned features are seen, except horizontal crypts. 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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  Low mag.
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  Intermed. mag.
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  High mag.

Another case:

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  Low mag.
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  Intermed. mag.
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  High mag.