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colorectal carcinoma in serrated polyposis syndrome

Monday 10 December 2012

In a series, 55.5% of cases with a residual contiguous serrated polyp
harbored the V600E mutation in BRAF.

It has been showed that the presence of conventional colorectal adenomas in SP was associated with the occurrence of CRC,
suggesting that at least some CRCs may develop from
conventional adenomas.

In a series, the majority of patients (88.9%) had at least 1 conventional adenoma identified separate from the CRC. However,
only 4 CRCs had a residual contiguous conventional adenoma, a relatively small number, possibly secondary to overgrowth of the precursor polyp by the carcinoma in some cases or because of insufficient tumor sampling.

This suggests that CRC in SP patients may develop from nonserrated polyps through either a derivative of the traditional adenoma pathway.

SP could therefore, potentially, be considered a disorder associated with a hypermature or inappropriately aged colonic mucosa, possibly secondary to an alteration in DNA methylation, with a resultant propensity to the development of early onset multiple serrated polyps and conventional adenomas.

The molecular subtype of CRC, which may develop in SP patients, will
reflect the histologic type of the precursor polyp, with a skewed distribution toward a higher frequency of BRAF-mutated serrated pathway CRC compared with the general population in which serrated polyps are not as common.

Reference

- Multiplicity and Molecular Heterogeneity of Colorectal Carcinomas in Individuals With Serrated Polyposis. Rosty C, Walsh MD, Walters RJ, Clendenning M, Pearson SA, Jenkins MA, Win AK, Hopper JL, Sweet K, Frankel WL, Aronson M, Gallinger S, Goldblatt J, Tucker K, Greening S, Gattas MR, Woodall S, Arnold J, Walker NI, Parry S, Young JP, Buchanan DD. Am J Surg Pathol. 2012 Dec 1. PMID: 23211288