Table of ContentsDefinition / general | Essential features | Terminology | Clinical features | Microscopic (histologic) description | Microscopic (histologic) images | Molecular / cytogenetics description | Sample pathology report | Differential diagnosis | Additional references | Board review style question #1 | Board review style answer #1
Cite this page: Feely M, Gonzalez RS. Serrated polyp. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/appendixserratedpolyps.html. Accessed September 25th, 2023.
Definition / general
- Benign serrated lesion of the appendix
- 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
- 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 @liverwei on Twitter
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.
- Appendiceal mucinous neoplasms:
- May demonstrate serrated features but will be associated with loss of the underlying muscularis mucosae
Board review style question #1
Serrated polyp of the appendix differs from sessile serrated polyp / adenoma of the colon in what way?
- It favors KRAS mutation over BRAF mutation
- It has a higher incidence
- It never shows cytologic atypia
- It only occurs in patients with Lynch syndrome
- It rarely loses MLH1 by immunohistochemistry