Colon polyps pathophysiology: Difference between revisions
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==Genetics== | ==Genetics== | ||
*The development of colon polyps is the result of multiple genetic mutations. | *The development of colon polyps is the result of multiple [[Mutation|genetic mutations]]. | ||
*Genetic mutations might cause hereditary polyps disorders. | *Genetic mutations might cause [[Heredity|hereditary]] polyps disorders. | ||
==== '''[[Familial adenomatous polyposis]] ([[FAP]])''' ==== | |||
* FAP is due to mutations in the following genes: | |||
** ''[[APC (gene)|APC]]'' gene, which is located on [[chromosome]] 5 in band q21 or band q22 (5q21-q22) | |||
** ''[[MUTYH]]'' gene, which is located on chromosome 1 between bands p34.2 and p32.1 (5p34.3-p32.1) | |||
** MYH-associated polyposis (MAP) is caused by mutations in the MYH gene. | |||
'''[[Peutz-Jeghers syndrome]]''' | |||
* It is thought that Peutz-Jeghers syndrome is the result of [[Deletion (genetics)|deletion]] or [[Deletion (genetics)|partial deletion]] of [[STK11]] (LBK1) gene, located on [[chromosome]] 19p13.3. | |||
'''[[Gardner's syndrome]]''' | |||
* It is caused by [[mutation]] in the [[APC gene]] located in [[chromosome]] 5q21 (band q21 on chromosome 5). | |||
'''Serrated polyposis syndrome''' | '''Serrated polyposis syndrome''' | ||
* They develop multiple serrated adenomatous polyps in the upper part of the colon. | * They develop multiple serrated adenomatous polyps in the upper part of the colon. | ||
*There has been some association with | ==== Familial juvenile polyposis ==== | ||
*There has been some association with following genes: | |||
**SMAD4 on [[Chromosome 18 (human)|chromosome 18]] | |||
**PTEN on [[Chromosome 10 (human)|chromosome 10]] | |||
==Gross Pathology== | ==Gross Pathology== | ||
*On gross pathology, | *On gross pathology, outpouching, pedunculated or flat lesions are characteristic findings of colon polyps. | ||
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==Microscopic Pathology== | ==Microscopic Pathology== | ||
==References== | ==References== | ||
{{Reflist|2}} | {{Reflist|2}} | ||
Revision as of 16:59, 22 January 2018
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Colon polyps Microchapters |
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Colon polyps pathophysiology On the Web |
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Risk calculators and risk factors for Colon polyps pathophysiology |
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Sadaf Sharfaei M.D.[2]
Overview
Pathophysiology
Pathogenesis
- Any form of unregulated growth in the colon may cause polyps. The exact etiology is unclear. However, risk factors may contribute to the formation of polyps.
- There are four different types of polyps including inflammatory, hamartomatous, serrated, and adenomatous polyps, which have different pathogenesis.
- The pathophysiology of colon polyps depends on the histological type.
- It is thought that colon polyps is mediated by either [hypothesis 2], or [hypothesis 3].
Inflammatory polyps
- Inflammatory polyps are non-neoplastic polyps that occur following intestinal inflammation, infections, or ischemia.[1][2]
- They mostly occur in patients with inflammatory bowel disease, mainly ulcerative colitis.
- They are considered as pseudopolyps which contain inflammatory infiltrations with distorted mucosa.
- It had no malignant potential. However, it is recommended to biopsy the lesion and surrounding mucosa.
- Microscopic pathology of biopsy shows mixture of normal, ulcerated, and regenerating mucosa which is surrounded by areas of mucosal loss.
Hamartomatous polyps
- Hamartomatous polyp is an overgrowth of mature cells and connective tissue elements including smooth muscle, lamina propria, and cartilage, and fat. They are covered by a hypertrophic epithelium.[3]
- They might be pedunculated, inflamed, or smooth polyps which are solitary or multiple.
- Solitary hamartomatous polyps, also known as juvenile polyps, can present more commonly in younger population.
- Solitary polyps has no significant risk of cancer. However, multiple polyps of the colon have a 10% risk of malignancy.
Serrated polyps
- Serrated polyps are different polyps which have variable malignant potential. They include hyperplastic, sessile serrated and traditional serrated polyps. They have various histopathologies and manifestations.
- Hyperplastic polyps are the most common polyps. They are small outpouching, less than 5 mm, which are located mostly in rectosigmoid area. Hyperplastic polyp is infolding of the crypt epithelium that forms serration or saw-toothed appearance. The molecular basis of this transformation is still unclear. However, it has been attributed to failure of apoptosis.
- Serration
- BRAF mutation
- KRAS mutation
- Sessile serrated polyps
- Traditional serrated adenomas
Adenomatous polyps
Genetics
- The development of colon polyps is the result of multiple genetic mutations.
- Genetic mutations might cause hereditary polyps disorders.
Familial adenomatous polyposis (FAP)
- FAP is due to mutations in the following genes:
- APC gene, which is located on chromosome 5 in band q21 or band q22 (5q21-q22)
- MUTYH gene, which is located on chromosome 1 between bands p34.2 and p32.1 (5p34.3-p32.1)
- MYH-associated polyposis (MAP) is caused by mutations in the MYH gene.
- It is thought that Peutz-Jeghers syndrome is the result of deletion or partial deletion of STK11 (LBK1) gene, located on chromosome 19p13.3.
- It is caused by mutation in the APC gene located in chromosome 5q21 (band q21 on chromosome 5).
Serrated polyposis syndrome
- They develop multiple serrated adenomatous polyps in the upper part of the colon.
Familial juvenile polyposis
- There has been some association with following genes:
- SMAD4 on chromosome 18
- PTEN on chromosome 10
Gross Pathology
- On gross pathology, outpouching, pedunculated or flat lesions are characteristic findings of colon polyps.
 |
Microscopic Pathology
References
- ↑ Shussman, N.; Wexner, S. D. (2014). "Colorectal polyps and polyposis syndromes". Gastroenterology Report. 2 (1): 1–15. doi:10.1093/gastro/got041. ISSN 2052-0034.
- ↑ Li SC, Burgart L (2007). "Histopathology of serrated adenoma, its variants, and differentiation from conventional adenomatous and hyperplastic polyps". Arch. Pathol. Lab. Med. 131 (3): 440–5. doi:10.1043/1543-2165(2007)131[440:HOSAIV]2.0.CO;2. PMID 17516746.
- ↑ Zbuk KM, Eng C (2007). "Hamartomatous polyposis syndromes". Nat Clin Pract Gastroenterol Hepatol. 4 (9): 492–502. doi:10.1038/ncpgasthep0902. PMID 17768394.
- ↑ "File:Image of resected colon segment with cancer & 4 nearby polyps plus schematic of field defects with sub-clones.jpg - Wikimedia Commons".