[693] Serrated Polyps in Patients with Inflammatory Bowel Disease

Lik Hang Lee, Christopher Andrews, Stefan Urbanski. University of Calgary, Calgary, AB, Canada

Background: Serrated polyps (SPs), comprised of sessile serrated adenomas (SSAs) and traditional serrated adenomas (TSAs), are known precursors of colorectal cancer. It is also known that inflammatory bowel disease (IBD) increases the risk of colorectal cancer. SPs have been reported to occur in IBD, but because SPs outside of IBD have a different molecular pathway and outcome than adenomas (tubular and villous), it may also represent a different natural history in IBD. However, the prevalence of SPs in IBD patients is unknown and no guidelines exist for their management. This project aims to establish the frequency and anatomic distribution of SPs in IBD.
Design: All IBD patients with a gastrointestinal (GI) biopsy performed at the regional tertiary care hospital, from January 1, 2007 to December 31, 2008, were identified through a search of the centralized health region pathology database. Among these patients, all who had a biopsy diagnosed as adenoma, hyperplastic polyp (HP), SSA, or TSA were selected and their histologic sections reviewed by one GI pathologist who was blinded to the original diagnosis. We did not try to differentiate between dysplasia-associated lesions or masses and sporadic adenomas. Each patient's records were reviewed to classify the anatomic distribution of the lesions (proximal or distal to the splenic flexure).
Results: 663 IBD patients with a GI biopsy were identified. 78 patients had a diagnosis of at least one of adenoma, HP, SSA or TSA after the pathology review (Table 1). There was a change in diagnosis for several polyps including 4 SSAs previously diagnosed as HPs, 1 SSA previously a “serrated adenoma”, 1 TSA previously an adenoma, and 1 TSA previously a “serrated adenoma”. None of the SSAs had dysplasia.

Table 1: Polyp type, location, and frequency

	Proximal (% of total)	Distal (% of total)	Total	% frequency in IBD patients
Adenoma	19 (43.2%)	25 (56.8%)	44	6.64%
HP	13 (27.1%)	35 (72.9%)	48	7.24%
SSA	6 (100.0%)	0 (0.0%)	6	0.90%
TSA	1 (33.3%)	2 (66.7%)	3	0.45%

Conclusions: Our study is the first retrospective cohort study to identify the frequency of SPs in IBD patients. It also allows comparison between the frequency of SPs, HPs, and adenomas. As expected, all 6 SSAs were located proximally, and 2 of the 3 TSAs were distal. There were 5 times fewer SPs than either HPs or adenomas. One still cannot address the question of whether SPs develop independent of IBD, or if IBD represents an increased risk of SPs. While the frequency of SPs in our study is higher than in the general population, this is of uncertain significance due to our limited population. We intend to follow up on our detected SPs with BRAF mutation analysis.
Category: Gastrointestinal

Tuesday, March 20, 2012 1:00 PM

Poster Session IV # 70, Tuesday Afternoon