Serrated polyposis is an underdiagnosed and unclear syndrome: the surgical pathologist has a role in improving detection

Abstract

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. We determined the frequency of SPS among patients with any serrated polyps (SPs) over a 6-month "index" period, and in doing so we assessed the ability of surgical pathologists to improve SPS detection. Particular attention was given to the index procedure to assess the potential predictive value of the findings resulting from a single colonoscopy. A total of 929 patients with at least 1 SP were identified, 17 of whom (1.8%) were determined to meet World Health Organization criteria for SPS. Nine patients met the first criterion (≥ 5 proximal SPs, 2 of which are > 10 mm); 4 met the third criterion (> 20 SPs of any size distributed throughout the colon); and 4 met both criteria. Although no specific SP size or number at the index procedure was clearly superior in its ability to predict SPS, > 50% of cases would be detected if a cutoff of ≥ 3 SPs or a single SP ≥ 15 mm at the index procedure is used. In summary, SPS is rare but more likely underdiagnosed. Additional studies to address the underlying genetic basis for SPS are ongoing in order to shed further light on this syndrome. Surgical pathologists are in a unique position to assist in this endeavor by identifying those patients who either meet or seem to be at high risk of meeting World Health Organization criteria.

Figure 1

Polyps diagnosed at index procedure in serrated polyposis patients, A (10x), B (20x), Tubular adenoma; C (10x), D (20x), Hyperplastic polyp with serration at the surface and narrow crypts at the base; E (10x), F (20x), Sessile serrated adenoma showing boot-shaped and transverse oriented crypts at the base without cytologic dysplasia; F (10x), G (20x), Sessile serrated adenoma showing dilated and boot-shaped crypts at the base without cytologic dysplasia.

Figure 2

Sessile serrated adenomas with dysplasia, A (10x), B (20x), The deep crypts show dilatation and transverse orientation while the surface epithelium contains conventional cytologic dysplasia; C (10x), D (20x), The right sides of the figures show sessile serrated adenoma while the left sides demonstrate surface cytologic dysplasia.

Figure 3

Utility of index serrated polyp number to predict the presence of serrated polyposis syndrome

Figure 4

Utility of index serrated polyp size to predict the presence of serrated polyposis syndrome