Large Intestine: Colon Polyps

Colon Polyps

Basics

  • Majority Are < 1.0 cm (60-75%)
  • Left-Sided Predominance

Size

  • Small: < 5 mm
  • Medium: 5-10 mm
  • Large: > 1-2 cm
  • Giant: > 3 cm

Paris Classification (Gross Appearance)

  • 0-I: Polypoid
    • 0-Ip: Pedunculated – Stalk at Base is Narrower than the Top
    • 0-Is: Sessile – Base Has the Same Diameter as the Top
  • 0-II: Nonpolypoid
    • 0-IIa: Slightly Elevated
    • 0-IIb: Flat – Height Less Than Half the Diameter
    • 0-IIc: Depressed – Depression within the Surrounding Mucosa
  • 0-III: Excavated – Ulcerated (High Risk of Malignancy)

Histologic Type

  • Hyperplastic
    • Normal Cellular Components with Proliferative Characteristics but No Dysplasia
    • Most Common Polyp
    • Characteristic Serrated (“Saw Tooth”) Pattern
    • Benign
  • Adenomas
    • Tubular Adenoma
      • > 75% Tubular Features – Network of Branching Adenomatous Epithelium
      • Most Common Neoplastic Polyp
      • Usually Pedunculated
    • Villous Adenoma Mn
      • > 75% Villous Features – Long Glands Extending from the Surface Straight Down
      • Most Likely to Produce Symptoms
      • 50% Have CA
    • Tubulovillous
      • ≥ 25% of Both Tubular & Villous Features
  • Hamartomas
    • Disorganized Growth of Normal Tissue Elements
    • Benign, But Can Degenerate to Adenomatous

Depth of Invasion Classification

  • Haggitt Classification
    • Depth of Invasion of a Malignant Pedunculated Polyp
    • Levels:
      • Level 0: Does Not Invade Muscularis Mucosae (In Situ)
      • Level 1: Invades Head
      • Level 2: Invades Neck
      • Level 3: Invades Stalk
      • Level 4: Invade Base or Involved in a Sessile Polyp
        • All Sessile Polyps with Invasive Carcinoma are Level 4
    • Risk of Lymph Node Metastasis:
      • Levels 1-3: < 1%
      • Level 4: 30%
  • Kikuchi Classification
    • Depth of Invasion of a Malignant Sessile Polyp
    • Levels:
      • SM1: Superficial Third
      • SM2: Middle Third
      • SM3: Deep Third
    • Risk of Lymph Node Metastasis:
      • SM1: Low Risk (2%)
      • SM2-3: High Risk (22-33%)

Nodular Lymphoid Hyperplasia

  • Numerous Polyps in Small & Large Intestine
  • Bx: Enlarged Submucosal Lymphoid Follicles
  • Benign but Associated with Immunosuppression (HIV)

Polyp Excision

  • Colon: Endoscopic Polypectomy
  • Rectum: Transanal Excision
  • If Ulcerated – Consider Optional Resection

Sessile Polyp 1

Pedunculated Polyp 2

Tubular Adenoma 3

Villous Adenoma 3

Mnemonics

Polyp Histology

  • Vile Villains: Villous More Malignant and Symptomatic

References

  1. Sagi SV, Ballard DD, Marks RA, Dunn KR, Kahi CJ. Bannayan Ruvalcaba Riley Syndrome. ACG Case Rep J. 2014 Jan 10;1(2):90-2. (License: CC BY-NC-ND-4.0)
  2. Agarwal P, Rai P, Jain M, Mishra S, Singh U, Gupta SK. Prevalence of colonic polyp and its predictors in patients with acromegaly. Indian J Endocrinol Metab. 2016 Jul-Aug;20(4):437-42. (License: CC BY-NC-SA-3.0)
  3. Shussman N, Wexner SD. Colorectal polyps and polyposis syndromes. Gastroenterol Rep (Oxf). 2014 Feb;2(1):1-15. (License: CC BY-3.0)