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Colonic Polyp

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Colonic Polyp, Colon Polyp, Adenomatous Colonic Polyp, Colorectal Adenoma, Hyperplastic Colonic Polyp, Sessile Serrated Adenomatous Colonic Polyp

  • See Also
  1. Colorectal Cancer Screening
  2. Colorectal Cancer Prevention
  3. Colorectal Cancer
  1. Benign
    1. Hyperplastic Colonic Polyp (except the higher risk, hyperplastic polyposis syndrome)
    2. Inflammatory Colonic Polyp
  2. Malignant Potential (require complete excision and close interval follow-up)
    1. Adenomatous Colonic Polyp
    2. Sessile Serrated Adenomatous Colonic Polyp
  • Types
  • Hyperplastic Polyp
  1. Account for 50% of sigmoid and rectal polyps
  2. Small (1-5 mm), sessile polyps
  3. Rare dysplasia risk (does not modify Colonoscopy screening intervals)
  • Types
  • Adenomatous Polyp
  1. Tubular adenomas (80%)
    1. Malignant transformation rate: 4-8%
  2. Tubulovillous adenoma
    1. Malignant transformation rate: 19%
  3. Villous adenoma
    1. Malignant transformation rate: 38.4%
  • Types
  • Sessile Serrated Adenomatous Polyp
  1. Precautions
    1. Primary pathway to hypermethylated gene cancers (20-30% of Colorectal Cancer)
    2. Must be completely excised and monitored as with adenomatous polyps
    3. Easily missed on Colonoscopy (flat, indiscrete lesions with adherent mucus)
    4. Higher malignant potential when proximal to the sigmoid colon
  2. Characteristics
    1. Typically larger than 1 cm, but typically flat
    2. Occurs in right colon in 75% of patients
    3. More common in women (65%)
    4. Accounts for 9% of all Colonic Polyps
  3. References
    1. Larson (2008) Mayo Selected Topics in Internal Medicine, Lecture
    2. Snover (2005) Am J Clin Path 124:380 [PubMed]
    3. Spring (2006) Gastroenterology 131: 1400-7 [PubMed]
  • Interpretation
  1. Factors suggesting higher risk of future adenomatous polyp (3 year follow-up)
    1. Three or more adenomatous polyps
    2. Adenomatous polyp or serrated polyp >1 cm
    3. Polyp biopsy consistent with high grade dysplasia or villous features
    4. Sessile serrated polyp with dysplasia
    5. Traditional serrated adenoma
  2. Factors suggesting lower risk of future adenomatous polyp (5-10 year follow-up)
    1. High quality baseline exam (see Colon Cancer Screening with Colonoscopy)
    2. Fewer than 3 adenomatous polyps
    3. Small adenomatous polyps <1 cm
    4. No high grade or villous changes
    5. Adenomatous polyps removed completely (not piecemeal)
  3. References
    1. Atkin (1992) N Engl J Med 326:658-62 [PubMed]
    2. Lieberman (2012) Gastroenterology 143(3): 844-57 [PubMed]
  • References
  1. Short (2014) Am Fam Physician 91(2): 93-100 [PubMed]