Benign tumors
Serrated polyps

Author: Michael Feely, D.O. (see Authors page)
Editor: Raul S. Gonzalez, M.D.

Revised: 7 August 2017, last major update July 2017

Copyright: (c) 2003-2017,, Inc.

PubMed Search: Appendix serrated polyps
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Cite this page: Serrated polyps. website. Accessed January 19th, 2019.
Definition / general
  • Benign serrated lesion of the appendix
Essential features
  • Benign appendix polyp that may show cytologic atypia / dysplasia
  • Harbors KRAS mutations
  • "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

Images hosted on Pathout server:
Missing Image

Serrated polyp of appendix, contributed by Michael Feely, D.O.

Molecular / cytogenetics description
Differential diagnosis
Additional references
Board review 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 answer #1
A. It favors KRAS mutation over BRAF mutation