Colon (tumor & nontumor)
Sessile serrated adenoma

Topic Completed: 1 January 2018

Minor changes: 31 July 2020

Copyright: 2003-2020,, Inc.

PubMed search: Sessile serrated adenoma [title]

Enoch Kuo, M.D.
Raul S. Gonzalez, M.D.
Page views in 2019: 23,756
Page views in 2020 to date: 12,573
Cite this page: Kuo E. Sessile serrated adenoma. website. Accessed August 14th, 2020.
Definition / general
  • Serrated neoplastic precursor lesion of colorectal cancer (Am J Gastroenterol 2012;107:1315)
  • Defined as having 2 or 3 contiguous crypts demonstrating features of sessile serrated adenoma, as discussed below (per Bosman: WHO Classification of Tumours of the Digestive System, 4th Edition, 2010)
  • Criteria for serrated polyposis syndrome include one of the following:
    • At least five serrated polyps proximal to the sigmoid colon with at least 2 greater than 1 cm in size
    • Any serrated polyp proximal to the sigmoid colon in a patient with a first degree relative with serrated polyposis syndrome
    • More than 20 serrated polyps of any size in the colon
Essential features
  • Neoplastic, premalignant lesion of the colorectum
  • If present, patient should undergo increased colonoscopy surveillance
  • May develop traditional cytologic dysplasia and progress to colorectal carcinoma with microsatellite instability
  • Current official WHO designation is sessile serrated lesion; former WHO designation was sessile serrated adenoma / polyp
  • Examples that develop adenomatous epithelium are termed "sessile serrated adenoma with cytologic dysplasia" (Gastrointest Endosc 2014;80:307)
ICD coding
  • ICD-10: K63.5 - Colon polyp
Clinical features
  • Incidental findings on colonoscopy and have no clinical features unless they progress to malignancy
Radiology description
Prognostic factors
Gross description
Gross images

Images hosted on other servers:

Sessile serrated adenoma on colonoscopy


Sessile serrated adenoma
before and after endoscopic

Microscopic (histologic) description
  • Sawtooth serrations of the epithelium with abundant mucin, similar to hyperplastic polyps
  • Basal crypt dilation with mucous retention
  • Bases of the crypts are more serrated compared to the surface and have mature goblet cells and mucinous cells (Am J Gastroenterol 2012;107:1315)
  • Lateral spread of the crypt bases (commonly described as boot shaped or anchor shaped crypts)
  • Conventional low grade or high grade dysplasia may also be present
Microscopic (histologic) images

Contributed by Raul S. Gonzalez, M.D.

Sessile serrated adenoma / polyp

Contributed by Christopher Hartley, M.D.

Sessile serrated adenoma with adenomatous dysplasia

Images hosted on other servers:

Sessile serrated adenoma / polyp

Ascending colon

Sessile serrated adenoma


Virtual slides

Images hosted on other servers:

Serrated adenoma with abnormal proliferation

Positive stains
Negative stains
Molecular / cytogenetics description
Differential diagnosis
Additional references
Board review style question #1
What mutations can be seen in sessile serrated adenoma?

  1. Beta-catenin and KRAS
  2. BRAF and beta-catenin
  3. BRAF and CpG island methylator phenotype (CIMP)
  4. KRAS and CpG island methylator phenotype (CIMP)
Board review answer #1
C. BRAF and CpG island methylator phenotype (CIMP). KRAS and beta-catenin mutations are not associated with sessile serrated adenomas and are instead seen in traditional serrated adenomas and tubular adenomas.

Reference: Colon tumor - Sessile serrated adenoma

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