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Table of Contents
Definition / general | Essential features | Terminology | Sites | Pathophysiology | Clinical features | Treatment | Microscopic (histologic) description | Microscopic (histologic) images | Molecular / cytogenetics description | Differential diagnosisCite this page: Feely M. Serrated polyposis. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/colontumorserratedpolyposissx.html. Accessed February 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
