title: Molecular and histologic considerations in the assessment of serrated polyps.
abstract: CONTEXT : Colorectal cancer is a heterogeneous disease resulting from different molecular pathways of carcinogenesis. Recent data evaluating the histologic features and molecular basis of the serrated polyp-carcinoma pathway have significantly contributed to more comprehensive classifications of and treatment recommendations for these tumors.
  
  
  OBJECTIVE
  To integrate the most recent molecular findings in the context of histologic classifications of serrated lesions and their implications in diagnostic pathology and colorectal cancer surveillance.
  
  
  METHODS
  Published literature focused on serrated polyps and their association with colorectal cancer.
  
  
  CONCLUSIONS
  Three types of serrated polyps are currently recognized: hyperplastic polyps, sessile serrated adenomas/polyps, and traditional serrated adenomas. The BRAF V600E mutation is one of the most frequent molecular abnormalities identified in hyperplastic polyps and sessile serrated adenomas. In contrast, in traditional serrated adenomas, either BRAF V600E or KRAS mutations can be frequently identified. CpG methylation has emerged as a critical molecular mechanism in the sessile serrated pathway. CpG methylation of MLH1 often leads to reduced or lost expression in dysplastic foci and carcinomas arising in sessile serrated adenomas/polyps.
authors.affiliation: From the Department of Pathology and Cell Biology, Columbia University, New York, New York.
authors.forename: Hui-Min
authors.initials: HM
authors.lastname: Yang
authors.forename: James M
authors.initials: JM
authors.lastname: Mitchell
authors.forename: Jorge L
authors.initials: JL
authors.lastname: Sepulveda
authors.forename: Antonia R
authors.initials: AR
authors.lastname: Sepulveda
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics; D000236:Adenoma / Q000235:genetics* / Q000473:pathology; D003111:Colonic Polyps / Q000235:genetics* / Q000473:pathology; D015179:Colorectal Neoplasms / Q000235:genetics* / Q000473:pathology; D019175:DNA Methylation; D006801:Humans; D000070957:MutL Protein Homolog 1; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics; D057089:Pathology, Molecular; D011518:Proto-Oncogene Proteins / Q000235:genetics; D048493:Proto-Oncogene Proteins B-raf / Q000235:genetics; D016283:Proto-Oncogene Proteins p21(ras); D018631:ras Proteins / Q000235:genetics
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C117307:KRAS protein, human; C501486:MLH1 protein, human; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf; D000070957:MutL Protein Homolog 1; D016283:Proto-Oncogene Proteins p21(ras); D018631:ras Proteins