Clinical Features of Colorectal Serrated Adenomas

ABSTRACT

PURPOSE: Colorectal cancer is believed to progress through an adenoma-carcinoma sequence. However, recent evidence increasingly supports the existence of an alternative route for colorectal carcinogenesis through a serrated adenoma, which combines the architectural features of hyperplastic polyps with the cytological features of traditional adenomas. We assessed the characteristics and the endoscopic features of serrated adenomas and compared them with those of hyperplastic polyps and traditional adenomas in Korea. METHODS: The medical records of 344 consecutive patients who underwent a colonoscopic biopsy or polypectomy from January 2003 through August 2004 at Gyeongsang National University Hospital were analyzed retrospectively. RESULTS: Serrated adenomas were seen in 12 cases (3.4%), and the most common site was the rectum (50%). Endoscopically in most cases, the serrated adenomas had small diameters (< or = 0.5 cm) and were single polyps. Morphologically, the serrated adenomas were flat and non-pedunculated. The coincidental rate of the carcinomas was 8.3%. CONCLUSIONS: According to this study, serrated adenomas are generally single, sessile adenomas with diameters less than 5 mm, and they are commonly observed in the left colon, especially in the rectum.