Serrated polyposis

Colon tumor
Familial polyposis syndromes
Serrated polyposis

Senior Author: Raul S. Gonzalez, M.D.

Topic Completed: 1 July 2016

Revised: 10 January 2019, last major update July 2016

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

PubMed Search: Serrated polyposis [title] colon tumor

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Table of Contents

Cite this page: Feely M. Serrated polyposis. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/colontumorserratedpolyposissx.html. Accessed June 18th, 2019.

Definition / general

Polyposis syndrome defined by the development of numerous sessile serrated polyps in the colon

Essential features

WHO diagnostic criteria: (a) at least five serrated polyps proximal to the sigmoid colon with two or more of these being > 10 mm; or (b) any number of serrated polyps proximal to the sigmoid colon in an individual who has a first degree relative with serrated polyposis; or (c) > 20 serrated polyps of any size, distributed throughout the colon
Significantly increased risk for colorectal carcinoma (Gut 2010;59:1094) and possibly extracolonic malignancies (Dis Colon Rectum 2011;54:164)
Family members also at increased risk for colorectal malignancies, suggesting an inherited component (Am J Gastroenterol 2012;107:770)
Likely represents a heterogeneous group of patients that includes several phenotypes of serrated polyposis

Terminology

Previously referred to as hyperplastic polyposis syndrome, although serrated polyposis is current preferred term by WHO

Sites

Polyps found throughout the large intestine, including in the appendix (Pathology 2016;48:30)

Pathophysiology

Likely consists of at least two groups: (Type 1) patients with BRAF mutations and relatively few large right sided polyps, and (Type 2) patients with KRAS mutations and many small left sided polyps (J Pathol 2007;212:378)
Awaiting more definitive molecular genetic studies

Clinical features

Mean age at diagnosis is 55 years, with overall equal distribution in males and females
Type 1 patients (with BRAF mutations) typically female smokers (United European Gastroenterol J 2016;4:305)
Typically asymptomatic and encountered on screening colonoscopy, although larger polyps may bleed
Most cases appear de novo, although a few familial cases have been described

Treatment

Colonoscopy for polyp removal every 1 - 3 years, depending on polyps present
Colectomy with ileorectal anastomosis in cases of advanced lesions or those not amenable to colonoscopic management
Some recommend screening colonoscopy in first degree family members (Am J Gastroenterol 2012;107:770)

Microscopic (histologic) description

Lesions typically consist of sessile serrated adenomas / polyps that may have cytologic dysplasia
Hyperplastic polyps, typically of the microvesicular type, are also encountered and may be large
Conventional adenomas are occasionally present and may represent sessile serrated adenomas / polyps with cytologic dysplasia

Microscopic (histologic) images

Images hosted on other servers:

Syndromic sessile serrated polyps, with no cytologic dysplasia (left)
and low grade cytologic dysplasia (right)

Molecular / cytogenetics description

In addition to BRAF and KRAS mutations (as above), RNF43 has recently been implicated in sporadic and familial sessile serrated polyps (Gut 2016 Jun 21 [Epub ahead of print])

Differential diagnosis

MUTYH associated polyposis: can also show serrated polyps, but the predominant lesions are conventional adenomas