title: p53 overexpression in flat serrated adenomas and flat tubular adenomas of the colorectal mucosa.
abstract: The expression of the p53 protein was investigated in flat serrated neoplasias as well as in other histological phenotypes of flat or exophytic hyperplasias or neoplasias of the colorectal mucosa. A total of 104 such lesions were analyzed: 24 were flat serrated neoplasias (22 flat serrated adenomas and 2 flat serrated adenocarcinomas), 26 flat tubular adenomas, 17 flat hyperplastic polyps, 29 exophytic tubular and/or villous neoplasias (23 adenomas and 6 exophytic adenocarcinomas) and the remaining 8, exophytic hyperplastic polyps. Deparaffinized, rehydrated sections were treated immunohistochemically to detect those overexpressing the p53 protein. Lesions having slight (+), moderate (++) or intense ( ) staining were considered immunoreactive. The results showed that 50% of the flat serrated adenomas with low-grade dysplasia (LGD) and 66.7% of those with high-grade dysplasia (HGD) had p53 immunoreactivity. None of the flat tubular or of the exophytic adenomas with LGD expressed p53, but immunoreactivity was present in 61.5% of the flat tubular adenomas with HGD and in 52.3% of the exophytic adenomas with HGD. All adenocarcinomas had an intense p53 reaction. Weak p53 expression was demonstrated by 11.7% of the flat hyperplastic polyps but none of the exophytic polyps reacted. The occurrence of p53 expression in flat serrated adenomas with LGD suggested that, despite its low histological profile, one-half of those lesions could be biologically already committed to independent growth. The occurrence of p53 expression in nearly 12% of the flat hyperplastic polyps was totally unexpected and deserves further investigation. Flat serrated adenoma emerges as a novel, independent histological entity among the various phenotypes of flat neoplasias of the colorectal mucosa.
authors.affiliation: Department of Pathology, Karolinska Institute, Stockholm, Sweden.
authors.forename: C A
authors.initials: CA
authors.lastname: Rubio
authors.forename: M
authors.initials: M
authors.lastname: Rodensjö
mesh_terms: D000230:Adenocarcinoma / Q000235:genetics*; D000236:Adenoma / Q000235:genetics*; D015179:Colorectal Neoplasms / Q000235:genetics*; D015870:Gene Expression; D016158:Genes, p53; D006801:Humans; D007124:Immunoenzyme Techniques; D012333:RNA, Messenger / Q000235:genetics
chemical_list: D012333:RNA, Messenger