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Colon tumor

Polyps

Hyperplastic polyp of colon


Reviewers: Charanjeet Singh, M.D. (see Reviewers page)
Revised: 16 May 2012, last major update May 2012
Copyright: (c) 2003-2012, PathologyOutlines.com, Inc.

General
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● 90% of all polyps
● Usually patients age 50+ years, often in rectosigmoid
● Present in 30-50% of normal individuals (85% of adults in Western world versus 2% in third world countries)
● Due to delayed shedding of surface epithelial cells
● Associated with cigarette smoking (Cancer Causes Control 2005;16:1021)
● Previously considered to have no / minimal malignant potential (Arch Intern Med 2005;165:382), except for those in hyperplastic polyposis syndrome
● Right sided hyperplastic polyps are molecularly more similar to serrated adenomas than to left sided hyperplastic polyps, and are associated with cancers that show microsatellite instability (but see J Clin Pathol 2004;57:1089)
● Intermediate (6-9 mm) sized polyps are usually right sided and are associated with synchronous colorectal carcinoma (J Gastroenterol Hepatol 2005;20:1572)

Case reports
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● 68 year old man with hyperplastic polyp containing small invasive carcinoma (Endoscopy 2004;36:825)

Gross description
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● Small (< 5 mm), sessile, usually on top of mucosal folds, multiple and same color as surrounding mucosa
● Lesions up to several cm may occur in right colon, but may be serrated adenomas

Gross images
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Hyperplastic polyp

Micro description
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● Well-formed, elongated glands and crypts with serrated (saw tooth) or star-shaped appearance resembling secretory endometrium
● Mixture of goblet cells (with abundant mucin) and absorptive cells
● Bland cytology with eosinophilic cytoplasm, well-defined brush borders and basal nuclei
● Thickened basement membrane; Paneth cells in 8%; may have multinucleated giant cells (Am J Surg Pathol 2005;29:912)
● Cells at base of crypt may have nuclear elongation, crowding and increased mitotic rate, but this is not adenomatous change
● May be splaying of muscularis mucosa fibers into submucosa
● Large hyperplastic polyps may have adenomatous foci

Micro images
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Right sided vs. left sided polyps


Serrated crypts

Various images #1, #2, #3, #4, #5

Virtual images
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Hyperplastic polyp

Molecular description
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● Limited changes, no relation to changes in co-existing adenomas (J Clin Pathol 2004;57:1084)


Hyperplastic polyp of colon with misplaced epithelium

General
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● Also called “pseudoinvasion”
● Some authorities consider it synonymous to inverted hyperplastic polyp, but others consider them different
● Simulates adenoma with pseudoinvasion, but benign
● Arises in left colon due to local trauma (torsion or twisting of polyp, vigorous peristalsis)

Micro description
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● Colonic epithelium in lamina propria with mixed pattern (lobules and irregularly distributed crypts) or lobular pattern
● Continuous with mucosal portion of polyp in deeper levels
● Defects are present in muscularis mucosa, and muscle fibers are splayed around misplaced epithelium
● Often lymphoid aggregates adjacent to misplaced epithelium, fresh hemorrhage, vascular congestion and hemosiderin deposits
● Usually no significant inflammation, no dysplasia

Micro images
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Misplaced epithelium

   
Left: Ki67 / MIB1; right: collagen IV

Positive stains
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Misplaced epithelium: Ki-67, E-cadherin and collagen IV basement membrane

Additional references
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Mod Pathol 2001;14:869


Inverted hyperplastic polyp of colon

General
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● More frequent in right colon
● May be more common in women

Case reports
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● Two middle aged men with inverted hyperplastic polyposis (J Clin Pathol 1993;46:56)
● Associated with adenoma (Eur J Gastroenterol Hepatol 2004;16:107)

Gross images
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Inverted polyposis

Micro description
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● Endophytic growth pattern, penetrates muscularis mucosa (Am J Surg Pathol 1985;9:265)

Micro images
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Inverted polyps #1; #2-associated with submucosal adipose; #3-large submucosal mucin cyst; #4-with epithelial displacement to lymphoid follicle


CEA+ (normal colon at upper right is CEA neg)

End of Colon tumor > Polyps > Hyperplastic polyp of colon


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