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For further information, see CMDT Part 15-37: Polyps of the Colon

Key Features

Essentials of Diagnosis

  • Discrete mass lesions that are flat or protrude into the intestinal lumen

  • Most commonly sporadic, may be inherited as part of familial polyposis syndrome

  • Of polyps removed at colonoscopy, over 70% are adenomatous; most of the remainder are serrated; distinguished by histology

General Considerations

  • Four major pathological groups

    • Mucosal adenomatous polyps (tubular, tubulovillous, villous)

    • Mucosal serrated polyps (hyperplastic, sessile serrated polyp, traditional serrated adenoma)

    • Mucosal nonneoplastic polyps (juvenile polyps, hamartomas, inflammatory polyps)

    • Submucosal lesions (lipomas, lymphoid aggregates, carcinoids, pneumatosis cystoides intestinalis)

  • Adenomas and serrated polyps may be flat, sessile, or pedunculated (containing a stalk)

    • They are present in 30% of adults over 50 years of age

    • Their significance is that over 95% of cases of adenocarcinoma of the colon are believed to arise from these lesions

  • Sessile serrated polyps and traditional serrated adenomas may harbor an increased risk of colorectal cancer similar or greater to that of adenomas and account for up to 20–30% of colorectal cancers

  • Small hyperplastic polyps (< 5 mm) located in the rectosigmoid region are of no consequence, except that they cannot reliably be distinguished from adenomatous lesions other than by biopsy

  • Hyperplastic polyps located in the proximal colon (ie, proximal to the splenic flexure) may be associated with an increased risk of neoplasia, particularly those > 1 cm

Clinical Findings

Symptoms and Signs

  • Usually asymptomatic

  • Chronic occult blood loss may lead to iron deficiency anemia

  • Large polyps may ulcerate, resulting in intermittent hematochezia

Differential Diagnosis

  • Colorectal cancer

  • Nonneoplastic polyp, eg, small hyperplastic, inflammatory

  • Submucosal polyp, eg, lipoma, lymphoid aggregate

  • Other causes of occult gastrointestinal bleeding, eg, arteriovenous malformation, inflammatory bowel disease


Laboratory Tests

  • Fecal occult blood test (FOBT), fecal immunochemical test (FIT), and fecal DNA tests

  • FIT is more sensitive than prior guaiac-based FOBT for the detection of colorectal cancer and advanced adenomas

  • Combination fecal DNA and FIT for stool hemoglobin (proprietary name: "Cologuard"); in a prospective comparative trial

    • Sensitivity for colorectal cancer for "Cologuard" was 92.3% compared to 73.8% for FIT

    • Sensitivity for large (> 1 cm) adenomas or serrated polyps for "Cologuard" was 42.4% compared to 23.8% for FIT

Imaging Studies

  • CT colonography ("virtual colonoscopy")

    • Has a sensitivity of ≥ 90% for the detection of polyps > 10 mm in size

    • However, the accuracy for detection of polyps 5–9 mm in size is significantly lower (sensitivity 50%)

  • Barium enema is no longer recommended due to its poor diagnostic accuracy

Diagnostic Procedures

  • Colonoscopy is best means of detecting and removing adenomatous polyps

  • Capsule endoscopy of the ...

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