Colon polyps
Classification and external resources
Polyp of sigmoid colon as revealed by colonoscopy. Approximately 1 cm in diameter. The polyp was removed by snare cautery
ICD-10	K63.5 & various
MedlinePlus	000266
eMedicine	med/414
MeSH	C23.300.825

Gross appearance of a colectomy specimen containing two colorectal polyps and one invasive colorectal carcinoma

A colorectal polyp is a polyp (fleshy growth) occurring on the lining of the colon or rectum.^[1] Untreated colorectal polyps can develop into colorectal cancer.^[2]

Colorectal polyps are often classified by their behaviour (i.e. benign vs. malignant) and/or etiology (e.g. as a consequence of inflammatory bowel disease). They may be benign (e.g. hyperplastic polyp), pre-malignant (e.g. tubular adenoma) or malignant (e.g. colorectal adenocarcinoma).

[edit] Types

The most common general classification is:

• hyperplastic,
• adenomatous & malignant,
• hamartomatous and,
• inflammatory.

[edit] Neoplastic polyp

Micrograph of a tubular adenoma, the most common type of dysplastic polyp in the colon.

Micrograph of a sessile serrated adenoma. H&E stain.

A neoplasm is a tissue whose cells have lost its normal differentiation. They can be either benign growths or malignant growths. The malignant growths can either have primary or secondary causes.

Neoplastic polyps of the bowel are often benign hence called adenomas. An adenoma is tumour of columnar cells or glandular tissue.

Neoplastic polyps can be further broken down into tubular, tubulovillous or villous. They are all broken down into these categories by histology (microscopic examination of tissue).

The villous subdivision is the worst because these have the greatest potential for malignancy. This is because the villi are projections into the lumen and hence have a bigger surface area and therefore a greater potential for malignant change.

[edit] Hamartomatous polyp

They are growths, like tumours found in organs as a result of faulty development. They are normally made up of a mixture of tissues. They grow at the normal rate of the host tissue and rarely cause problems such as compression. A common example of a hamartomatous lesion is a strawberry naevus. Hamartomatous polyps are often found by chance; occurring in syndromes such as Peutz-Jegher or Juvenile Polyposis Syndrome.

Peutz-jeghers syndrome is associated with polyps of the GI tract and also increased pigmentation around the lips, genitalia, buccal mucosa feet and hands. People are often diagnosed with Peutz-Jegher after presenting at around the age of 9 with an intussusception. The polyps themselves carry little malignant potential but because of potential coexisting adenomas there is a 15% chance of colonic malignancy.

Juvenile polyposis syndrome are polyps which often present when the patient is young hence called juvenile. Patients normally present young with rectal bleeding. Polyps can be solitary or multiple (>5). If there are multiple the condition is then referred to as Juvenile Polyposis. This condition may have a genetic association. Patients require upper and lower endoscopic screening with removal of polyps. If you fear adenomatous tissue developing then you can offer surgery, namely colectomy and ileorectal anastomosis

[edit] Inflammatory polyp

These are polyps which are associated with inflammatory conditions such as Ulcerative Colitis and Crohns disease.

[edit] Symptoms

Colorectal polyps are not usually associated with symptoms.^[2] When they occur, symptoms include rectal bleeding, bloody stools, abdominal pain and fatigue.^[2] A change in bowel habits may occur including constipation and diarrhoea.^[3] Occasionally, if a polyp is big enough to cause a bowel obstruction, there may be nausea, vomiting and severe constipation.^[3]

[edit] Screening and diagnosis

Micrograph of a tubular adenoma – dysplastic epithelium (dark purple) on left of image; normal epithelium (blue) on right. H&E stain.

Micrograph of a villous adenoma. These polyps are considered to have a high risk of malignant transformation. H&E stain.

Colorectal polyps can be detected using a faecal occult blood test, flexible sigmoidoscopy, colonoscopy, virtual colonoscopy, digital rectal examination, barium enema or a pill camera.^[3]

[edit] When does a polyp become a problem?

Malignant potential is associated with

• degree of dysplasia
• Type of polyp (e.g. villous adenoma):
  • Tubular Adenoma: 5% risk of cancer
  • Tubulovillous adenoma: 20% risk of cancer
  • Villous adenoma: 40% risk of cancer
• Size of polyp:
  • <1 cm =<1% risk of cancer^{[citation needed]}
  • 1 cm=10%risk of cancer^{[citation needed]}
  • 2 cm=15%risk of cancer^{[citation needed]}

Normally an adenoma which is greater than 0.5 cm is treated

[edit] Treatment

Polyps can be removed during a colonoscopy or sigmoidoscopy using a wire loop that cuts the stalk of the polyp and cauterises it to prevent bleeding.^[3] Many "defiant" polyps—large, flat, and otherwise laterally spreading adenomas—may be removed endoscopically by techniques that involve injection of fluid underneath them, to lift them and thus enable them to be taken out. These techniques, when they may be employed, are an alternative to a much-more-invasive colectomy.^[4]

[edit] Structure

Polyps are either pedunculated (attached to the intestinal wall by a stalk) or sessile (grow directly from the wall).^[5]

[edit] Additional images

Hyperplastic polyp. H&E stain.

Hyperplastic polyp. H&E stain.

[edit] References

[edit] External links

• "How I Do It" — Removing large or sessile colonic polyps. Dr. Brian Saunders MD FRCP; St. Mark’s Academic Institute; Harrow, Middlesex, UK. Retrieved April 9, 2008.
• http://www.netdoctor.co.uk/diseases/facts/colonpolyps.htm
• http://www.clevelandclinic.org/registries/inherited/jp.htm

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