Colon polyps are growths of the lining of the colon. Most of the colon polyps are benign, but some can become cancerous over time. There are several types of colon polyps. The most common ones are:
Serrated polyps are characterized by the “saw-toothed” architecture under microscope. More recent studies about serrated polyps suggest they have different pathways to progress to cancer compared to other types of polyps. They comprise a group of lesions, including:
- Hyperplastic polyps (HPs). HPs in the distal part of the colon are usually benign, except hyperplastic polyposis syndrome.
- Sessile serrated adenomas (SSAs)
- Traditional serrated adenomas (TSAs)
- Mixed lesions
Most of the colon polyps are adenomas. They have malignant potential and need to be removed if found. They comprise a group of lesions, including:
- Tubular adenoma
- Villous adenoma
- Tubulovillous adenomas (see picture at right)
Hamartomatous polyps are normally made up of a mixture of tissues.
- Peutz-Jegher 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.
- Juvenile Polyposis Syndrome. Juvenile polyposis syndrome is characterized by the presence of more than five polyps in the colon or rectum, or numerous juvenile polyps throughout the gastrointestinal tract, or any number of juvenile polyps in any person with a family history of juvenile polyposis. Juvenile polyposis increases risk of colon cancer. Patients with Juvenile polyposis syndrome usually present as rectal bleeding.
Polyps associated with an inherited disorder
Familial adenomatous polyposis (FAP). This is a rare, inherited disorder that grows hundreds to thousands of polyps in the GI tract beginning at teenage years. The risk of developing colon cancer is nearly 100 percent before age 40.
- Gardner's syndrome. This is a variant of FAP. The characters of this syndrome is that besides the polyps in the GI tract, there are also tumors in other parts of your body, including your skin, bone, etc.
- MYH-associated polyposis (MAP). This inherited condition is similar to FAP.
- Lynch syndrome. Lynch syndrome is also called hereditary nonpolyposis colorectal cancer (HNPCC), which is the most common form of inherited colon cancer.
- Hyperplastic polyposis syndrome. It is a rare condition but has great risk of cancer. According to the World Health Organization, Hyperplastic polyposis syndrome is defined as either:
- Five or more hyperplastic polyps proximal to the sigmoid colon, with two polyps greater than 10mm in diameter; or
- Any number of hyperplastic polyps proximal to the sigmoid colon in a person with a first degree relative who has hyperplastic polyposis syndrome; or
- More than 30 hyperplastic polyps of any size throughout the colon and rectum.
Causes and Risk Factors
Common ones are:
- Ulcerative colitis
- Crohn’s disease
- High animal fat diet
- Low fiber diet
- Alcohol consumption
- Inherited genetic disorders
Symptoms and Signs
Most colon polyps are silent, which means they do not produce any symptoms. Sometime they may cause the following symptoms:
- Rectal bleeding
- Invisible blood in the stool
- Abdominal pain or discomfort
- Obstruction symptoms, such as abdominal pain, nausea, vomiting, etc, if the polyp is large enough to block the lumen of the large bowel.
Diagnosis, Screening, and Treatment
- Diagnosis is based clinical presentation with one or more of the following tests:Blood works
- Stool studies
Screening is recommended beginning at age of 50 years old for all, with some special groups at an earlier age. Screening colonoscopy has been proven to be an very effective method to prevent colon cancer. Other alternative methods are:
- Barium enema
- Stool test for occult blood
- CT colonography
Treatment is to remove the polyp(s) if indicated based on appearance and pathology finding with periodic monitoring. Colonoscopy and Flexsigmoidoscopy are good ways to remove polyps. Pictures at upper right show the removal of a 2 cm tubulovillous adenoma through a colonoscopy. Larger polyps or cancerous polyps may need surgery resection.
- Mayo clinic online health information.
- Sleisenger and Fordtran's Gastrointestinal and Liver Disease- by Mark Feldman MD, et al.
- The Little Black Book of Gastroenterology-by David W. Hay.
- Principles of Clinical Gastroenterology by Tadataka Yamada, et al.