Updated: 12/15/2021

Colonic Polyps

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  • Snapshot
    • A 60-year-old healthy man undergoes a screening colonoscopy. He has been staying active, does not smoke, denies any bloody or dark stools, changes in stool, abdominal pain, or fatigue. His prior colonoscopy was normal. During today‚Äôs colonoscopy, his gastroenterologist notes a small pedunculated growth in the descending colon.
  • Introduction
    • Overview
      • abnormal growth of tissue from the colonic mucosa
        • most are benign but some can progress to cancer
        • treatment is resection
      • can be part of a polyposis syndrome
        • familial adenomatous polyposis
        • juvenile polyposis syndrome
        • Peutz-Jeghers syndrome
        • Gardner syndrome
    • Genetics
      • APC
      • KRAS
      • T53
      • BRAF
      • microsatellite instability
      • mismatch repair
  • Epidemiology
    • Incidence
      • highly prevalent (30-50% of adults)
      • 90% occur after 50 years of age
      • can be hyperplastic and benign or adenomatous with malignant transformation
        • up to 90% are hyperplastic polyps
      • most commonly in sigmoid and rectum
    • Risk factors
      • smoking
      • obesity
      • high-fat diet
      • red meat
  • ETIOLOGY
    • Pathogenesis
      • pathophysiology
        • hyperplastic polyp
          • non-dysplastic proliferation of the colonic epithelium
        • adenomatous polyp
          • growth and malignant transformation with genetic mutations
          • can be tubular, tubulovillous, villous, or sessile serrated
            • villous has the greatest malignant potential
  • Presentation
    • Symptoms
      • most often asymptomatic
      • common symptoms
        • rectal bleeding
        • change in stool caliber
    • Physical exam
      • inspection
        • endoscopically visualized
      • provocative tests
        • digital rectal exam
          • occult blood
          • palpated if distal
  • Imaging
    • Lower gastrointestinal radiograph series
      • may detect larger polyps
    • Virtual colonoscopy with computed tomography scan
      • limited use outside of research
      • may detect larger polyps
      • poor sensitivity
  • Studies
    • Serum labs
      • tumor markers
        • CEA
        • CA19-9
        • associated but not used for screening or diagnosis
    • Invasive studies
      • stool occult blood test
        • neither sensitive nor specific
      • endoscopic evaluation
        • colonoscopy is the best evaluation
        • alternatives include flexible sigmoidoscopy or pill capsule endoscopy
        • obtain a biopsy for pathological evaluation
    • Histology
      • H&E of endoscopic biopsy samples is diagnostic
        • size
        • degree of dysplasia
  • Differential
    • Inflammatory bowel disease
      • key distinguishing factor
        • pseudopolyp from the scarring process in response to inflammation
    • Familial adenomatous polyposis
      • key distinguishing factors
        • many polyps
        • younger age
    • Peutz-Jeghers syndrome
      • key distinguishing factors
        • hamartomatous polyps
        • mucocutaneous hyperpigmentation
  • Treatment
    • Surgical
      • endoscopic polypectomy
        • indications
          • for all visualized polyps
      • colectomy
        • indications
          • endoscopically unresectable polyps
          • multiple large adenomas
          • high-grade dysplasia
          • invasive adenocarcinoma
          • severe gastrointestinal bleeding
  • Complications
    • Gastrointestinal bleeding
    • Adenocarcinoma of the colon
      • risk factors
        • time undetected
      • treatment
        • depends on stage
  • Prognosis
    • Natural history
      • malignant progression of adenomatous polyps can take years
    • Good progosis with polypectomy

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