Colon tumor
Polyps
Inflammatory polyp of colon

Author: Andrew L.J. Dunn, M.D.
Editor: Raul S. Gonzalez, M.D.

Revised: 7 December 2017, last major update November 2017

Copyright: (c) 2002-2017, PathologyOutlines.com, Inc.

PubMed Search: "Inflammatory polyp" colon

Related topics: Giant inflammatory polyp / polyposis of colon, inflammatory polyp of colon secondary to mucosal prolapse
Cite this page: Dunn, A.L.J. Inflammatory polyp of colon. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/colontumorinflammatory.html. Accessed February 18th, 2018.
Definition / general
Essential features
  • Nonneoplastic colon polyp composed of inflamed mucosa
  • Typically shows surface erosion with surrounding granulation tissue and epithelial distortion
Terminology
ICD-10 coding
  • K51.4 inflammatory polyps of colon
Epidemiology
  • Typically second and third decades for inflammatory bowel disease; incidence range of 10 - 20% in ulcerative colitis patients (World J Gastroenterol 2017;23:1541)
  • May occur in older patients with peripheral vascular disease
Sites
  • Can arise anywhere in the colon, especially at the ileocecal region in Crohn’s disease
  • May form at anastomotic sites
Pathophysiology
  • Believed to be secondary to repeated bouts of intense inflammation
  • Formation of inflammatory polyps may be related to increases in C-reactive protein, C4 and procollagen III peptide (World J Gastroenterol 2003;9:619)
Clinical features
  • Sporadic inflammatory polyps are usually incidental at colonoscopy
  • May present with intussusception or obstructive symptoms
  • Presence of pseudopolyps in inflammatory bowel disease may represent recent flare, although lesions are found in active or dormant disease (World J Gastroenterol 2017;23:1541); also may be related to arthropathy or other extracolonic symptoms (Lancet 1969;2:555)
Case reports
Treatment
  • Typically treated endoscopically via polypectomy
  • Examples related to inflammatory bowel disease may improve with infliximab (J Crohns Colitis 2010;4:707)
  • Argon plasma coagulation or ablation for bleeding control
  • Surgical resection if profuse bleeding, obstruction or intussusception
Clinical images

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Endoscopy of inflammatory polyp in the sigmoid colon

Gross description
  • Usually sessile and less than 3 cm
  • May be pedunculated or filiform
Gross images

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Inflammatory pseudopolyps in ulcerative colitis

Microscopic (histologic) description
  • Often consists of normal colonic mucosa in a polypoid configuration, with increased inflammation (expanded lamina propria and crypt abscesses or cryptitis)
  • Epithelium can show various degrees of surface erosion, crypt distortion / dilation or hyperplasia, along with reactive nuclear features within the mucosal epithelial cells
  • May consist entirely of granulation tissue (abundant thin walled and dilated vessels surrounded by mixed neutrophilic and lymphoplasmacytic inflammation)
  • Reactive stromal cells may be markedly pleomorphic and mimic sarcoma
  • Cases associated with inflammatory bowel disease may rarely show epithelial dysplasia
Microscopic (histologic) images

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Images contributed by Andrew L.J. Dunn, M.D.

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Ulcerative colitis



Annotated images

Negative stains
Molecular / cytogenetics description
  • Usually no abnormalities
Videos

Inflammatory polyp on colonoscopy

Differential diagnosis
Board review question #1
Which of the following is NOT a typical feature of inflammatory polyps?

  1. Crypt distortion / branching
  2. Granulation tissue changes
  3. Microsatellite instability
  4. Surface mucosal erosion
Board review answer #1
C. Microsatellite instability; inflammatory polyps are a benign process with various degrees of mucosal erosion, increased vascular density similar to granulation tissue and architectural changes.