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Ectopic crypt foci in conventional and serrated colorectal polyps
  1. Sara A Väyrynen1,2,
  2. Juha P Väyrynen1,2,
  3. Kai Klintrup2,3,
  4. Jyrki Mäkelä2,3,
  5. Anne Tuomisto1,2,
  6. Markus J Mäkinen1,2
  1. 1Cancer and Translational Medicine Research Unit, University of Oulu, Oulu, Finland
  2. 2Oulu University Hospital and Medical Research Center Oulu, Oulu, Finland
  3. 3Research Unit of Surgery, Anesthesia and Intensive Care, University of Oulu, Oulu, Finland
  1. Correspondence to Professor Markus J Mäkinen, Cancer and Translational Medicine Research Unit, University of Oulu, POB 5000, Oulu FI-90014, Finland; markus.makinen{at}


Aims Despite almost pathognomonic status of ectopic crypt foci (ECF) in the diagnosis of traditional serrated adenoma (TSA), there are few systematic studies on their prevalence in other types of colon polyps or in adenomas adjacent to colorectal cancer (CRC).

Methods We calculated ECF in all the polyps (n=922) removed in the colonoscopy in Oulu University Hospital in 2001. Moreover, to study ECF in precursor lesions next to CRCs, we re-examined a previously described cohort of 148 CRCs.

Results ECF were seen in 53 (5.7%) polyps representing 28 (6.5%) tubular adenomas (TAs), 14 (53.8%) tubulovillous adenomas (TVAs), 2 (100.0%) villous adenomas (VAs) and 9 (100.0%) TSAs. In all TSAs and VAs, the density of ECF was higher than in TVAs and TAs. An adjacent precursor lesion was recognised in 28 of 148 (18.9%) CRCs. Twenty-four (85.7%) of these contained ECF.

Conclusions ECF can most frequently be observed in TSAs but also in many TVAs, VAs and TAs, reflecting a histological overlap between serrated and conventional polyps. Especially, precursor lesions adjacent to CRC frequently contain ECF.


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  • Handling editor Cheok Soon Lee

  • Contributors Conception and design: MJM, SAV. Collection of the data and manuscript review and editing: all authors. Data analysis: SAV, JPV. Manuscript draft: SAV.

  • Funding This study was supported by grants from the Finnish Medical Foundation, Ida Montin Foundation, Orion Research Foundation, and Vatsatautien tutkimussäätiö. The funders had no role in the study design; in the collection, analysis and interpretation of the data; in the writing of the report; and in the decision to submit the paper for publication

  • Competing interests None declared.

  • Ethics approval All the experiments were conducted in accordance with the Declaration of Helsinki and with the approval of the Ethical Committee of Oulu University Hospital (58/2005, 184/2009).

  • Provenance and peer review Not commissioned; externally peer reviewed.