Objectives: The ability to differentiate histological characteristics between serrated polyps (SPs) and make a pathological diagnosis of a sessile serrated polyp (SSP) is highly variable. Recent studies have shown that immunohistochemical (IHC) expression of Annexin A10 (ANXA10) is a marker of a SSP. However, the clinical utility of ANXA10 expression in patients with SPs is unknown. The objective of this study was to evaluate the utility of ANXA10 expression in SPs in predicting the development of subsequent polyps at follow-up colonoscopy. Methods: Specimens from patients with SPs assessed in the Department of Pathology between 2006 and 2010 were identified. Patients whose colon harbored only SPs including either an SSP and/or hyperplastic polyp (HP) and who had complete polyp resection, no remaining polyps, and a follow-up colonoscopy were analyzed. ANXA10 IHC expression was performed in all baseline SPs. The rate of metachronous polyps on follow-up colonoscopy based on baseline maximal ANXA10 expression (low vs. high) was determined. Results: One hundred and seventy-nine patients were included. Sixty-seven patients had SPs with low ANXA10 expression (30 SSP and 37 HP) and 112 had polyps with high ANXA10 expression (105 SSP and 7 with HP). Individuals with SPs with high ANXA10 expression had a threefold higher risk of SSP on follow-up colonoscopy (hazard ratio (HR)=2.7; P=0.048) particularly, in the proximal colon (HR=4.0; P=0.02). ANXA10 expression did not predict patients at an increased risk of subsequent adenomas (18.8% vs. 19.4%, P=0.52). Conclusions: Individuals who harbor SPs with high ANXA10 expression are at an increased risk of metachronous serrated neoplasms. ANXA10 may be a reproducible tool to stratify patients with SPs into higher- and lower-risk groups of metachronous serrated neoplasia, allowing a more aggressive colonoscopic surveillance in patients at high risk.
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