Colonic polyps

Colonic polyps are abnormal colonic mucosal overgrowths. They are most common in people over 50 years of age but can also be found in younger patients who have hereditary polyposis syndromes. Affected individuals are typically asymptomatic but may present with gastrointestinal (GI) bleeding, iron deficiency anemia, and/or mechanical bowel obstruction (e.g., due to intussusception). Colonic polyps are classified macroscopically as either pedunculated (i.e., with a stalk) or sessile (i.e., without a stalk). They are classified histologically as adenomatous (most common), hyperplastic, inflammatory, serrated, or hamartomatous. Colonoscopy, which enables direct visualization biopsy and removal of the polyp, is the first-line diagnostic and therapeutic modality. Polyp removal is recommended because, although this condition is typically benign, it may transform to colorectal cancer. Adenomas (e.g., adenoma-carcinoma sequence) have the highest malignancy potential (∼ 5%). Patients with polyps that are concerning for malignancy and/or a history of familial adenomatous polyposis syndrome often require surgical resection. Regular follow-up surveillance is required following the removal of the polyps.

• Age
  • ∼ 30% of individuals > 50 years
  • Incidence increases with age.
• Frequency
  • ∼ 70%: adenomatous polyps
  • ∼ 20%: hyperplastic polyps
  • < 10%: other kinds of polyps (traditional serrated adenomas, sessile serrated adenomas, and mixed mucosal polyps)
• Sex: ♂ > ♀
• Race: more common in Black populations ^[1]

References: ^[2]

Epidemiological data refers to the US, unless otherwise specified.

The exact etiology is unknown. Risk factors include the following: ^[1]

• Lifestyle
  • Diet: high in red meat and fat; low in fiber and folic acid
  • Obesity and lack of exercise
  • Cigarette smoking
  • Alcohol consumption
• Genetic predisposition: hereditary polyposis syndromes

Macroscopic classification of colonic polyps

• Pedunculated: attached to the GI mucosa by a stalk
• Sessile: have a broad base (no stalk)

Histologic classification of colonic polyps

The majority of colon carcinomas develop from adenomas (adenoma‑carcinoma sequence). However, only ∼ 5% of adenomas develop into colon cancers.

Villous adenomas are villains because they have the highest malignant potential.

• Mostly asymptomatic
• If symptomatic:
  • Hematochezia (the most common symptom)
  • Change in bowel habits (constipation/diarrhea)
  • Mucus in stool
  • Pallor
  • Palpable rectal polyps on digital rectal exam
  • Bowel obstruction

Hereditary polyposis syndromes ^[8][9][10]

• Consist of adenomatous polyposis syndromes; and hamartomatous polyposis syndromes
• Associated with:
  • Increased risk of colon cancer
  • Tumors in other parts of the GI tract
  • Extraintestinal manifestations (e.g., tumors, cysts, cardiac conditions, pigmentation changes)
• After diagnostic confirmation of hereditary polyposis syndromes, the following are recommended: ^[11]
  • Referral to gastroenterology
  • Surveillance for intestinal and extraintestinal malignancies
  • Referral of the patient and at-risk family members for genetic counseling ^[8]

At-risk family members who decline genetic testing should undergo the same endoscopic surveillance as individuals with known mutations. ^[8]

Adenomatous polyposis syndromes ^[8][9][10]

Colonoscopy, not sigmoidoscopy, is the first-line screening modality for individuals with attenuated FAP or MUTYH-associated polyposis because these conditions typically manifest with proximal colonic polyps. ^[8][9][10]

Counsel patients on the course of polyposis syndromes and the need for adherence to surveillance protocols. ^[8]

The Turban covers the head: Turcot syndrome is associated with malignant brain tumors.

Hamartomatous polyposis syndromes ^[9][10]

25% of patients with hamartomatous polyposis syndromes have no family history (i.e., de novo mutation), and ≥ 10% of patients have negative genetic testing. ^[10]

Nonhereditary polyposis syndromes

Serrated polyposis syndrome ^[5][9][18]

• Definition: a condition in which multiple serrated polyps form in the colon; associated with an increased risk of colon cancer
• Prevalence: ∼1:100,000 ^[9][18]
• Etiology
  • Unclear; smoking may be a risk factor ^[5]
  • Familial association may be present; no gene has been identified ^[18]
• Diagnostic findings: serrated polyps throughout the colon ^[18]
• Management ^[9]
  • Surveillance colonoscopy every 1–3 years with polypectomy of all polyps > 5 mm ^[9]
  • Surgery (colectomy with ileorectal anastomosis) may be required if there are too many polyps to manage endoscopically.

Cronkhite-Canada syndrome ^[19][20]

• Definition: an extremely rare form of nonhereditary hamartomatous polyposis; associated with an increased risk of colorectal cancer ^[19]
• Etiology: unclear; likely immune-mediated
• Clinical features: typically manifests in individuals ∼ 60 years of age ^[19]
  • Symptoms of colonic polyps, including gastrointestinal hemorrhage
  • Protein-losing enteropathy
  • Extraintestinal manifestations ^[21]
    • Ectodermal changes
    • Sepsis
    • Congestive heart failure
• Diagnostic findings: numerous hamartomatous polyps; inflammatory changes within polyps
• Management
  • Nutritional support for protein loss from chronic diarrhea
  • Consider immune suppression with glucocorticoids or azathioprine.
  • Cancer screening: optimal intervals unclear, colonoscopy usually performed annually ^[20]

Approach

• Request for all patients with suspected polyps (e.g., positive family history, symptoms of colonic polyps):
  • CBC for anemia
  • Colonoscopy with polypectomy/biopsy
    • Confirmatory test
    • Alternatives include flexible sigmoidoscopy, CT colonoscopy, and double-contrast barium enema ^[22][23]
• Send any samples for histologic classification of colonic polyps.
  • No concerning features: Further treatment is not required.
  • Malignant features: Treat as colorectal cancer.
  • Features of hereditary polyposis syndromes: Refer to gastroenterology and genetics. ^[9][10]
• Follow-up is required for all patients because of the increased risk of malignancy.

Polyps are often identified as an incidental finding on workup for other conditions.

Patients with red flags for colon cancer or positive colorectal cancer screening tests (e.g., fecal occult blood testing) should undergo diagnostics for colorectal cancer.

Colonoscopy ^[24][25]

Colonoscopy facilitates simultaneous diagnosis and management of most polyps; suspected malignant colorectal polyps should be biopsied and referred to surgery.

• No polyps present
  • No hereditary polyposis syndrome: Consider differential diagnostics.
  • Hereditary polyposis syndrome: Arrange surveillance colonoscopy.
• Polyps present
  • Stratify risk to determine if polypectomy or biopsy is appropriate.
  • Advanced endoscopy techniques (e.g., chromoendoscopy, narrow-band imaging) may be required to identify high-risk features.

Patients with hereditary polyposis syndromes with multiple polyps that cannot be managed endoscopically should also be referred for surgery.

Endoscopic colon polypectomy ^[24][25]

Techniques

• Snare polypectomy
  • A thin wire snare encircles the polyp including a surrounding margin of healthy tissue.
  • The snare is then retracted, which causes it to tighten and cut through the encircled tissue.
  • Can be performed with electrocautery (i.e., hot snare) or without (i.e., cold snare)
• Endoscopic mucosal resection
  • The submucosa under the polyp is injected to lift the polyp away from the deeper mucosa.
  • A snare procedure is then performed to excise the polyp.

Complications ^[24][25][28]

• Postpolypectomy bleeding: lower gastrointestinal bleeding that occurs up to 30 days postpolypectomy ^[24]
  • Risk factors include: ^[24]
    • Patient: anticoagulant use, chronic renal disease, cardiovascular disease
    • Lesion: size ≥ 10 mm, located in ascending colon, pedunculated with thick stalk
  • Management
    • Intraprocedural bleeding: See “Endoscopic hemostasis.”
    • Postprocedural bleeding
      • Stabilize patients with hemorrhagic shock.
      • Consult gastroenterology urgently. ^[28][29]
      • See “Management of GI bleeding.”
  • Prophylactic measures
    • Periprocedural management of oral anticoagulant therapy for patients on anticoagulants
    • Ligation of pedunculated polyps ≥ 20 mm prior to removal
    • Injection of a vasoconstrictor (e.g., epinephrine) ^[24]
• Bowel perforation
• Postpolypectomy coagulation syndrome
  • Thermal injury to the bowel wall causes inflammation that leads to fever, localized abdominal pain, and elevated WBC count.
  • Normally self-limiting with supportive treatment (e.g., fluids, antibiotics, bowel rest)

Surgical resection ^[24][25][30]

• Colon resection may be required for suspected ; or confirmed malignancy (see “Surgery for colorectal cancer”).
• Hereditary polyposis syndromes may require ; surgical polyp removal (e.g., for large polyps) and/or colonic resection.

Refer patients with low-risk polyps that are difficult to remove (e.g., due to size and/or location) to an endoscopist with experience in advanced endoscopic removal techniques prior to referring to surgery. ^[24]

Follow-up ^[31][32]

The guidance in this section is for patients with no additional risk factors. For individuals at high risk of CRC, follow colorectal cancer screening in high-risk individuals. For individuals with hereditary polyposis syndromes, follow condition-specific screening procedures (see “Subtypes and variants”).

Follow-up should be tailored to the histology of the colonic polyp and the patient's risk factors for colorectal cancer.

• One-Minute Telegram 68-2023-3/3: They tested their poo, but didn’t follow through
• One-Minute Telegram 62-2022-3/3: Colonoscopy for colorectal cancer screening saves lives, but only if you get one

Interested in the newest medical research, distilled down to just one minute? Sign up for the One-Minute Telegram in “Tips and links” below.