Precancerous polyps are also known as adenomatous polyps. They look like the normal lining of the stomach but have different characteristics under the microscope. Most polyps of the colon are benign, but adenomas can develop into cancer. Adenomatous polyps by themselves are not cancer but can turn cancerous if not resected.
Tubular adenomas: Tubular adenomas are rounded neoplastic lesions with smooth surfaces. It is a common occurrence in adults. Small tubular adenomas are virtually benign, but lesions > 2 cms are at risk of developing a carcinoma. These adenomas collect APC, DCC, p53 and K-ras mutations over many years.
Villous adenomas: Villous adenomas are large and can be associated with severe dysplasia. They occur in the rectum and rectosigmoid with a potential to occur anywhere in the colon. Often there are no findings on physical examination, but a digital rectal examination may reveal a palpable mass. In the event of a villous adenoma of the ampulla, jaundice may be seen.
Tubulovillous adenomas: The TVA has a mixture of growth patterns of tubular and villous adenomas and is so called tubulovillous adenoma. Villous growth patterns can indicate the development of cancer in them.
Typical diagnostic tests will include:
- Faecal occult blood testing
- Genetic studies
- Imaging tests
Double contrast barium enema: polyp detectionincreases with sensitivity to the double-contrast enema as compared to single-contrast barium enemas
Computer tomographic colonography: it is a virtual colonoscopy with an advantage of being less invasive
Upper GI series: small bowel adenomas and polypoid lesions are detected on the upper GI series and small bowel follow-through
Video capsule endoscopy: helps assess the small bowel
Colonoscopy: to charactarise the polyps, to find the extent of the disease and to take biopsies.
Flexiblesigmoidoscopy examinations lead to follow-up colonoscopy for the detection of other polyps. The process is done after cleaning the colon and is recommended every 2 years to 3 years. A total colectomy is done for FAP followed by a proctoscopy every six months.