Serrated lesions of the large intestine: Prevalence analysis and clinical and morphologic characteristics

Abstract

to retrospectively estimate the prevalence of serrated lesions of the large intestine and to reveal the features of dis- tribution of serrated lesions in the previously diagnosed classical adenomas and hyperplastic polyps. A continuous sampling method was used to take biopsy specimens from the archive material of 440 polypoid lesions of the large intestine, which had entered in 2012-2013, and which were be morphologically reexamined by three experts. The mor- phological criteria for diagnosing different types of serrated lesions were taken according to the 2010 WHO classification of premalignant lesions of the large intestine and to the recommendations from an expert panel (Am J of Gastroenterology 2012). A group of serrated lesions included tubular (13.7%), tubulovillous adenomas (12.5%), and villous (50%) adenomas. The reexamination revealed 121 serrated lesions, including hyperplastic polyps (n = 55 (45.5%)), sessile serrated adenomas/ polyps (SSA/P) (n = 24 (19.8%)), out of which there were those with dysplasia (n=6 (5%)), traditional serrated adenomas (TSAs) (n = 20 (16.5%)), out of which there were those with dysplasia (n = 1 4 (11.6%)), and unclassified serrated polyps (n =22 (18.2%)). Most hyperplastic polyps (89%) and SSA/P (71%) were located distal to the splenic flexure of the colon; TSAs were equally distributed between the proximal and distal portions of the large intestine. The proportion of serrated lesions with dysplasia was 16.5%; that among SSA/P and TSAs was 25 and 70%, respectively. Serrated lesions with dysplasia were more often located proximally and were larger in size than those without dysplasia. Serrated lesions of the large intestine are its more common abnormalities than previously thought. The reexamination has revealed that serrated lesions occur in both the preexisting group of hyperplastic polyps and all groups of classical adenomas, suggesting the need for widespread introduction of the current classification intO everyday diagnostic practice.