RESUMO
INTRODUCTION: Patients with ulcerative colitis (UC) develop not only UC-associated neoplasias but also sporadic neoplasias (SNs). However, few studies have described the characteristics of SNs in patients with UC. Therefore, this study aimed to evaluate the clinical features and prognosis of SNs in patients with UC. METHODS: A total of 141 SNs in 59 patients with UC, detected by surveillance colonoscopy at Hiroshima University Hospital between January 1999 and December 2021, were included. SNs were diagnosed based on their location, endoscopic features, and histopathologic findings along with immunohistochemical staining for Ki67 and p53. RESULTS: Of the SNs, 91.5% were diagnosed as adenoma and 8.5% were diagnosed as carcinoma (Tis carcinoma, 3.5%; T1 carcinoma, 5.0%). 61.0% of the SNs were located in the right colon, 31.2% were located in the left colon, and 7.8% were located in the rectum. When classified based on the site of the lesion, 70.9% of SNs occurred outside and 29.1% within the affected area. Of all SNs included, 95.7% were endoscopically resected and 4.3% were surgically resected. Among the 59 patients included, synchronous SNs occurred in 23.7% and metachronous multiple SNs occurred in 40.7% during surveillance. The 5-year cumulative incidence of metachronous multiple SNs was higher in patients with synchronous multiple SNs (54.2%) than in those without synchronous multiple SNs (46.4%). CONCLUSION: Patients with UC with synchronous multiple SNs are at a higher risk of developing metachronous multiple SNs and may require a closer follow-up by total colonoscopy than patients without synchronous SNs.