Morphologic reappraisal of serrated colorectal polyps

Am J Surg Pathol. 2003 Jan;27(1):65-81. doi: 10.1097/00000478-200301000-00008.


The "hyperplastic polyp" is considered a benign lesion with no malignant potential, whereas "serrated adenoma" is a precursor of adenocarcinoma. The morphologic complexity of the serrated adenoma varies from being clearly adenomatous to being difficult to distinguish from hyperplastic polyp, which creates a need for more detailed morphologic analysis of all serrated polyps. We evaluated 24 morphologic variables in 289 serrated polyps from the colon and rectum. Cluster analysis and discriminant analysis were performed. A subset of polyps was immunostained for hMLH1 and hMSH2. Major differences were found between right-sided and left-sided polyps. A distinct group of serrated polyps with abnormal proliferation was identified throughout the colon and rectum. These polyps demonstrated decreased expression of hMHL1 and hMSH2 compared with polyps with normal proliferation. Left-sided serrated polyps with normal proliferation further clustered into three groups: vesicular cell-type, goblet cell-type, and mucin-poor-type. We recommend evaluation of the localization, size, and morphologic features when serrated polyps are included in colorectal carcinogenesis research. Polyps with abnormal proliferation are similar to the polyps in "hyperplastic polyposis" and, because of their decreased expression of hMLH1 and hMSH2, may be the subset of polyps associated with the development of colorectal carcinoma via the microsatellite instability pathway.

MeSH terms

  • Adaptor Proteins, Signal Transducing
  • Adenocarcinoma / metabolism
  • Adenocarcinoma / pathology*
  • Adenoma / metabolism
  • Adenoma / pathology
  • Carrier Proteins
  • Cell Division
  • Cluster Analysis
  • Colonic Polyps / metabolism
  • Colonic Polyps / pathology*
  • Colorectal Neoplasms / metabolism
  • Colorectal Neoplasms / pathology*
  • DNA-Binding Proteins*
  • Discriminant Analysis
  • Humans
  • Hyperplasia
  • Immunohistochemistry
  • MutL Protein Homolog 1
  • MutS Homolog 2 Protein
  • Neoplasm Proteins / metabolism
  • Nuclear Proteins
  • Precancerous Conditions / metabolism
  • Precancerous Conditions / pathology*
  • Proto-Oncogene Proteins / metabolism


  • Adaptor Proteins, Signal Transducing
  • Carrier Proteins
  • DNA-Binding Proteins
  • MLH1 protein, human
  • Neoplasm Proteins
  • Nuclear Proteins
  • Proto-Oncogene Proteins
  • MSH2 protein, human
  • MutL Protein Homolog 1
  • MutS Homolog 2 Protein