Appendix
Benign tumors
Serrated polyp


Topic Completed: 13 April 2021

Minor changes: 21 April 2021

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PubMed Search: Appendix serrated polyp

Michael Feely, D.O.
Raul S. Gonzalez, M.D.
Page views in 2020: 4,951
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Cite this page: Feely M, Gonzalez RS. Serrated polyp. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/appendixserratedpolyps.html. Accessed May 8th, 2021.
Definition / general
  • Benign serrated lesion of the appendix
Essential features
  • Benign appendix polyp that may show cytologic atypia / dysplasia
  • Harbors KRAS mutations
Terminology
  • Serrated polyp is currently preferred terminology over sessile serrated adenoma / polyp, as appendiceal lesions appear to have different mutations than similar lesions in the colon (Am J Surg Pathol 2016;40:14)
  • Presence or absence of dysplasia should be noted
Clinical features
  • Typically an incidental finding at the time of appendectomy
Microscopic (histologic) description
  • Localized serrated epithelial lesion within the luminal appendix, with retention of the muscularis mucosae
  • Often circumferential
  • Typically minimal to no nuclear atypia, though visible cytologic dysplasia (low grade or high grade) may sometimes be present
Microscopic (histologic) images

Contributed by Michael Feely, D.O.
Missing Image

Serrated polyp of appendix

Molecular / cytogenetics description
Sample pathology report
  • Appendix, appendectomy:
    • Serrated polyp with cytologic low grade dysplasia
    • Negative for malignancy.
    • Margin of resection negative for serrated polyp.
    • Background acute appendicitis.
Differential diagnosis
Additional references
Board review style question #1
Serrated polyp of the appendix differs from sessile serrated polyp / adenoma of the colon in what way?

  1. It favors KRAS mutation over BRAF mutation
  2. It has a higher incidence
  3. It never shows cytologic atypia
  4. It only occurs in patients with Lynch syndrome
  5. It rarely loses MLH1 by immunohistochemistry
Board review style answer #1
A. It favors KRAS mutation over BRAF mutation

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