Clinicopathological Analysis Of Serrated Adenomas Of The Colorectum

摘要

Background: Serrated adenoma is a recently recognized epithelial neoplasm of the colorectum. The aim of this study is to clarify the clinical and morphological features of serrated adenomas. Methods: Our study comprised of 44 cases of serrated adenoma that were signed-out during the year 1998; these were then divided into three histological groups according to histological features (tubular, tubulovillous or villous). These cases were looked for any synchronous associated histological lesion in the colorectum. The follow-up biopsies were also analyzed for each individual case and were correlated. Results: The mean age of presentation was 65.1 years with 1.5:1 male to female ratio. The tubular type of serrated adenoma was the predominant type with 34 cases (77%). There were eight cases (18%) of tubullovillous type and two cases (4.5%) of villous type. Majority of the lesions were limited to left colon (34% sigmoid and 41% rectum). On follow-up biopsies 3 cases developed adenocarcinoma, 1 case developed adenoma with high-grade dysplasia, 9 cases had recurrent adenomas and 3 cases had hyperplastic polyps. Conclusions: Serrated adenomas were mostly limited to the left colon and their clinical behavior correlated with their histological features. Introduction It has been generally understood that hyperplastic polyps of the colorectum are non-neoplastic, benign lesions. However, reports of cases with hyperplastic polyposis complicated by colorectal cancers1,2,3,4 and the presence of dysplasia in hyperplastic polyps5,6,7 have suggested that these benign lesions are prone to neoplastic transformation.In 1984, Urbanski et al.8 reported a case of colonic adenocarcinoma arising within a polyp of mixed hyperplastic and adenomatous morphology, and they referred to this lesion as a mixed hyperplastic and adenomatous polyp. A similar colonic lesion but with a different nomenclature “mixed hyperplastic and neoplastic polyp” was reported in 1986.9 Subsequently, Longacre and Fenoglio- Preiser10 published a report on 110 colorectal polyps with architecturally hyperplastic but cytologically neoplastic features, and they referred to these lesions as “serrated adenoma.” A serrated glandular pattern of adenomatous proliferation was the common characteristic feature of serrated adenoma.Although the serrated adenoma has become an established entity in the field of pathology, the clinical and morphological features of these polyps are not very well discussed. The aim of this study is to analyze the demographic, clinical, anatomical and follow-up features of serrated adenoma. Patients And Methods I reviewed pathology records at my institution from the period between January 1998 and December 1998 and sorted out the list of patients with serrated adenoma. The histologic diagnosis of serrated adenoma was based on the criteria described by Longacre and Fenoglio-Preiser.10 In brief, histologic confirmation of (1) a serrated glandular pattern simulating hyperplasia, (2) the presence of goblet cell immaturity, (3) upper crypt zone mitosis, and (4) the prominence of nuclei were the criteria for inclusion.10 The lesions fulfilling the above criteria were included in the investigation. Total 44 cases were found during the one-year period. These patients comprised 4% of 1095 colorectal adenomas found during this period. Results There were 27 (61.3%) men and 17 (38.6%) women; their ages at the time of diagnosis ranged from 33 to 85 years, with a mean age of 65.1 years. Synchronous traditional adenoma was found in 39 patients. None of the patients had synchronous invasive colorectal cancer or any family history suggestive of hereditary colorectal cancer syndromes. All 44 patients had a single serrated adenoma. Eleven patients also had synchronous hyperplastic polyp.Thirty-three (74%) of 44 adenomas were found in the rectosigmoid colon. The exact locations were 3 cases in cecum, 3 cases in ascending colon, one case in hepatic flexure, 2 cases in transverse colon, 2