Serrated polyps of the colon: the Winnipeg experience

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Bay, Diane
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BACKGROUND: The pathological distinction between hyperplastic polyps and sessile serrated adenoma/polyps of the right colon is often difficult and may result in misdiagnosed polyps. OBJECTIVE: To review the proportion and accuracy of serrated polyp diagnosis within a one year retrospective review of colorectal polyp samples, focusing on hyperplastic polyps of the right colon, using criteria set forth by previous studies. MATERIALS & METHODS: 4096 Winnipeg patient cases from January 2009 to December 2009 were reviewed. The proportion of sessile serrated adenoma/polyps, traditional serrated adenoma and serrated adenoma were determined in the patient population. Additionally, pathological morphological variables were reassessed by two study pathologists to determine the frequency of sessile serrated adenoma/polyp initially diagnosed as hyperplastic polyps within the right colon. RESULTS: Approximately 5% of all polyps in the patient population where diagnosed as non-hyperplastic serrated polyps (SSA/P, TSA and SA) and 12.5% as hyperpalstic polyps. Of the non-hyperplastic serrated polyps, a majority were diagnosed as SA. Upon reassessment of right sided HP (n=121), 34% were re-classified as SSA/P. CONCLUSIONS: Winnipeg pathologists diagnose non-hyperplastic serrated polyps with a frequency similar to literature, but are not fully utilizing modern terminology, as majority of non-hyperplastic serrated polyps are reported as SA without further categorisation. Furthermore, a significant proportion of right sided hyperplastic polyps could be re-classified as sessile serrated adenomas on review. Given the difficulty in distinguishing sessile serrated adenomas from hyperplastic polyps, closer endoscopic surveillance should be considered for all individuals with all serrated polyps (including hyperplastic polyps) in the right colon or alternatively all such polyps should be routinely reviewed by two pathologists.