Traditional serrated adenoma

Deputy Editor-in-Chief: Catherine E. Hagen, M.D.
Enoch Kuo, M.D.
Raul S. Gonzalez, M.D.

Last author update: 29 October 2021
Last staff update: 6 May 2022

Copyright: 2003-2023,, Inc.

PubMed Search: Colon tumor traditional serrated adenoma [title]

Enoch Kuo, M.D.
Raul S. Gonzalez, M.D.
Page views in 2022: 27,417
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Cite this page: Kuo E, Gonzalez RS. Traditional serrated adenoma. website. Accessed September 27th, 2023.
Definition / general
Essential features
  • Neoplastic polyp of the colon
  • Shows dysplastic appearing nuclei and prominent eosinophilic cytoplasm
ICD coding
  • ICD-10: K63.5 - Colon polyp
  • ICD-10: D12 - Benign neoplasm of colon, rectum, anus and anal canal (subcodes depending on site of adenoma)
  • May arise from microvesicular hyperplastic polyps (MVHP) and sessile serrated adenomas (SSA) (Hum Pathol 2015;46:933)
  • Generally considered to be intrinsically dysplastic, though some argue against this view (Hum Pathol 2015;46:933)
Clinical features
  • Incidental finding on colonoscopy
Radiology description
  • Screening CT colonography may identify large (~14 mm) traditional serrated adenomas (Radiology 2016;280:455)
Prognostic factors
  • Endoscopic removal of the adenoma
  • US Multi Society Task Force on Colorectal Cancer recommends a 3 year surveillance interval after initial diagnosis of traditional serrated adenomas (Gastroenterology 2012;143:844)
Gross description
Microscopic (histologic) description
  • Protuberant villiform growth pattern with slit-like serrations
  • Pseudostratified epithelial columnar cells with eosinophilic cytoplasm and dark, pencillate, dysplastic-like nuclei
  • Ectopic crypt foci / formations are a key feature (abnormally positioned crypts with bases not seated at the muscularis mucosae) (Am J Surg Pathol 2008;32:21)
  • High grade adenomatous dysplasia may be present
  • Goblet cells present
  • Mucin rich variant is characterized by > 50% goblet cells and fewer ectopic crypt formations (Histopathology 2017;71:208)
Microscopic (histologic) images

Contributed by Enoch Kuo, M.D.
Missing Image Missing Image

Traditional serrated adenoma

Contributed by Christopher Hartley, M.D.

Traditional serrated adenoma

Positive stains
Negative stains
Molecular / cytogenetics description
  • MAPK pathway activation is a critical initiating event, either by a BRAF or KRAS mutation (Hum Pathol 2015;46:933)
  • MAPK pathway activation is followed by CpG island methylator phenotype (CIMP)
  • BRAF mutated traditional serrated adenomas are more frequently CpG island methylator phenotype high (Mod Pathol 2015;28:414, Hum Pathol 2015;46:933)
  • Most cases have no defects in mismatch repair (microsatellite stable)
  • PTPRK-RSPO3 gene fusions may be present (Histopathology 2017;71:601)
Sample pathology report
  • Rectum, polypectomy:
    • Traditional serrated adenoma
Differential diagnosis
  • Hyperplastic polyp and sessile serrated adenoma:
    • Cytologic features of pseudostratification and nuclear elongation are most useful in distinguishing traditional serrated adenomas from hyperplastic polyps and sessile serrated adenomas (Virchows Arch 2012;461:495)
    • Ectopic crypts, goblet cells and eosinophilic cytoplasm are not distinguishing features since they may be present in sessile serrated adenomas and hyperplastic polyps as well (Am J Gastroenterol 2012;107:1315, Diagn Pathol 2014;9:212)
    • Traditional serrated adenomas can be distinguished from sessile serrated adenomas and hyperplastic polyps by their low Ki67 staining, specifically within the ectopic crypts (Am J Surg Pathol 2008;32:21)
  • Tubulovillous adenoma:
    • Definitive dysplastic nuclei, no eosinophilic cytoplasm, no serrated architecture or ectopic crypts
    • Tubulovillous adenomas often have a component resembling traditional serrated adenoma, with significance unclear
Board review style question #1
Which mutation is most common in traditional serrated adenomas?

  1. BRAF mutation
  2. CDKN2A mutation
  3. KRAS mutation
  4. TP53 mutation
Board review style answer #1
A. BRAF and KRAS mutations in traditional serrated adenomas are almost mutually exclusive with approximately 67% having BRAF mutations and 22% with KRAS mutations. BRAF mutated traditional serrated adenomas are more likely to be CpG island methylator phenotype high. TP53 mutation and CDKN2A silencing by methylation are seen in areas with conventional dysplasia (Mod Pathol 2015;28:414).

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