The significance of ectopic crypt formation in the differential diagnosis of colorectal polyps

Diagn Pathol. 2014 Nov 25:9:212. doi: 10.1186/s13000-014-0212-x.


Background: Ectopic crypts, defined as abnormally positioned crypts that have lost their orientation toward the muscularis mucosae, have been suggested to be the best defining histologic feature of traditional serrated adenoma (TSA). However, the significance of ectopic crypt formation (ECF) in the distinction between TSA and conventional adenoma (CA) has rarely been studied.

Methods: We designed this study to determine if ECF can be found in CA and its presence is exclusive to TSA. We studied 107 TSAs and 191 CAs including 106 tubular adenomas (TAs), 66 tubulovillous adenomas (TVAs), and 19 villous adenomas (VAs).

Results: ECF was identified in most (79.4%) but not all TSAs. Additionally, ECF was not infrequent in CA (62 of 191, 32.5%), and its presence correlated with the presence of a villous component and larger tumor size (each p <0.001).

Conclusions: Based on its strong association with the presence of a villous component and larger tumor size, ECF appears to be involved in the protuberant growth of colorectal CA. Because ECF can be found in CA, particularly in cases with a villous component, the possibility of CA should be considered before making a diagnosis of TSA when encountering colorectal polyps with ECF.

Virtual slides: The virtual slide(s) for this article can be found here:

Publication types

  • Comparative Study

MeSH terms

  • Aberrant Crypt Foci / genetics
  • Aberrant Crypt Foci / pathology*
  • Aberrant Crypt Foci / surgery
  • Adenomatous Polyps / genetics
  • Adenomatous Polyps / pathology*
  • Adenomatous Polyps / surgery
  • Adult
  • Aged
  • Aged, 80 and over
  • Biopsy
  • Colonic Polyps / genetics
  • Colonic Polyps / pathology*
  • Colonic Polyps / surgery
  • DNA Mutational Analysis
  • Diagnosis, Differential
  • Female
  • Humans
  • Male
  • Middle Aged
  • Mutation
  • Predictive Value of Tests
  • Proto-Oncogene Proteins / genetics
  • Proto-Oncogene Proteins B-raf / genetics
  • Proto-Oncogene Proteins p21(ras)
  • Tumor Burden
  • ras Proteins / genetics


  • KRAS protein, human
  • Proto-Oncogene Proteins
  • BRAF protein, human
  • Proto-Oncogene Proteins B-raf
  • Proto-Oncogene Proteins p21(ras)
  • ras Proteins