serrated polyposis syndrome

Definition: Serrated polyposis (SP) is a clinically defined syndrome characterized by the occurrence of multiple serrated polyps in the large intestine. Individuals with SP and their relatives are at increased risk of colorectal carcinoma (CRC).

Serrated polyposis syndrome (SPS) is poorly defined and patients have an increased but unspecified risk for colorectal carcinoma through the serrated pathway.

Despite this association SPS remains relatively obscure and is therefore likely underrecognized.

The majority of CRCs arising in individuals with SP do not harbor molecular hallmarks of "serrated pathway CRCs" but show a diverse range of molecular profiles. (23211288)

The high proportion of multiple CRCs suggests that individuals with SP would benefit from frequent colonoscopic surveillance and from a consideration of a more extensive colectomy at the time of CRC diagnosis. (23211288)

Serrated polyposis (SP) is a CRC predisposition syndrome with an established familial risk for CRC but without a known genetic basis.

The hallmark of SP is the presence of multiple serrated polyps (hyperplastic polyps and sessile serrated adenomas/polyps) in the large intestine.

It was suggested that the polyp burden and the co-occurrence of conventional adenomas increased the risk of CRC in patients with SP.

Endoscopy

Chromoendoscopy in the SPS should be carried out by spraying contrast over the entire surface of the colon and using a magnification endoscope.

The most widely used contrast is indigo carmine, which accumulates in pits and innominate grooves of the colonic mucosa, outlining the limits of flat lesions and drawing the described Kudo patterns.

Hyperplastic and serrated polyps typically show Kudo type I  (normal) or type II (‘‘stellate’’ or ‘‘papillary’’).

Published randomized trials have shown that pancolonic chromoendoscopy almost doubles the rate of detection of sporadic serrated polyps compared to conventional endoscopy.

In these studies, hyperplastic polyps (HPs) were found in 20% of patients using chromoendoscopy vs 10% of patients with conventional endoscopy, and this difference was statistically significant.

New endoscopic technologies, such as NBI and confocal laser endomicroscopy (CLE) should also be taken into consideration.

It is accepted that the vascular pattern evaluation by chromoendoscopy or NBI could be an appropriate method to differentiate adenomas from hyperplastic polyps (HPs), but it has not been specifically studied in the SPS.

In this way, Boparai et al ran a prospective series including 7 patients with SPS who underwent a colonoscopy with trimodal imaging (high resolution, AFI and NBI): they obtained an unsatisfactory diagnostic accuracy for differentiate between HPs and SSAs but distinguishing adenomas from HPs was possible with NBI (accuracy 94%).

Highest accuracy (76%) was achieved by the combination of a size of 3 mm or larger and a proximal location.

Comparing CLE with virtual chromoendoscopy, it was shown that CLE demonstrated higher sensitivity (91% vs 77%; P = 0.010) with similar specificity in histological classification of colorectal polyps.

However, further studies are needed to implement the CLE in clinical practice. The limited field of view and the horizontal sections of CLE hinder the detection of architectural distortion of sessile polyps.

References

 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

 Serrated Polyposis Is an Underdiagnosed and Unclear Syndrome: The Surgical Pathologist has a Role in Improving Detection. Crowder CD, Sweet K, Lehman A, Frankel WL. Am J Surg Pathol. 2012 Aug;36(8):1178-85. PMID: 22790859

 Hyperplastic/serrated polyposis in inflammatory bowel disease: a case series of a previously undescribed entity. Srivastava A, Redston M, Farraye FA, Yantiss RK, Odze RD. Am J Surg Pathol. 2008 Feb;32(2):296-303. PMID: 18223333