The Development of Serrated Epithelial Change in Ulcerative Colitis is not Significantly Associated with Increased Histologic Inflammation.

Serrated epithelial change (SEC) in inflammatory bowel disease is most often defined as hyperplastic polyp-like mucosal change detected on random biopsies. Although SEC has been reported to be associated with an increased risk of synchronous and/or metachronous colorectal neoplasia, it remains unknown if SEC represents a form of dysplastic lesion despite the lack of morphologic evidence of dysplasia. Since the risk of colorectal neoplasia in ulcerative colitis (UC) is positively correlated with increased histologic inflammation, this study investigated if increased colonic inflammation is an independent risk factor for SEC. A cohort of 28 UC patients with SEC was analyzed and compared with 51 control UC patients without SEC. None of these patients had a history of colorectal neoplasia. For each patient with SEC, all biopsies conducted before and at the time of SEC diagnosis (versus all biopsies for each control patient) were scored by using a 4-point scoring system: no activity (no epithelial infiltration by neutrophils=0); mild activity (cryptitis only=1); moderate activity (cryptitis plus crypt abscess formation in <50% of crypts=2); and severe activity (crypt abscess formation in ≥50% of crypts, erosion, neutrophilic exudate, and/or ulceration=3). Each biopsy was designated a score, and both mean and maximum inflammation scores were calculated from all biopsies taken during each colonoscopy. The inflammation burden score was calculated for each surveillance interval by multiplying the average maximum score between each pair of surveillance episodes by the length of the surveillance interval in years. The average scores of all colonoscopies for each patient were used to assign the patient's overall mean, maximum, and inflammation burden scores. The SEC cohort included 12 (43%) men and 16 (57%) women with a mean age of 47 years at the time of the first SEC diagnosis and a long history of UC (mean: 13 y). The majority of patients (n=21; 75%) had pancolitis, and only 1 (4%) patient had primary sclerosing cholangitis. A total of 37 SEC were identified in the 28 patients, 4 (14%) of whom had multifocal SEC. SEC was predominantly found in the left colon (n=32; 86%). In the multivariate analysis, none of the 3 summative inflammation scores, including overall mean (odds ratio [OR] 1.9, P=0.489), maximum (OR 0.4, P=0.259), and inflammation burden scores (OR 1.2, P=0.223), were significantly associated with the development of SEC. Similarly, no other potential risk factors, including age, gender, ethnicity, and duration and extent of UC, were significantly correlated with the detection of SEC (P>0.05). In conclusion, the development of SEC in UC is not significantly associated with increased histologic inflammation. Given the reported association of SEC with an increased risk of synchronous and/or metachronous colorectal neoplasia, along with the presence of molecular alterations in some cases (such as TP53 mutations and aneuploidy), SEC may represent an early morphologic indicator of segmental or pan-colonic molecular abnormalities that have not advanced enough to result in colorectal neoplasia, as opposed to being a form of dysplasia.