Colon and rectal polyps

A polyp is a macroscopically visible circumscribed growth or growth that projects onto the mucosal surface.

Historical background

The importance of rectal and colon polyps lies essentially in their relationship with cancer that affects these areas of the digestive tract.

In 1927 Lockhart-Mummery and Dukes published a study that related rectal and colon cancer to adenomatous tissue, that is, to abnormal tissue that constitutes the substrate for the most frequent type of polyp with malignant potential: the adenomatous polyp. In the 1970s, the concept of a polypo-carcinoma sequence was clearly established, which in turn serves as the basis for early detection studies in order to investigate and treat this disease in its earliest stages.

Classification

a) According to histology

1. Epithelial neoplastic polyp or adenomatous polyps or adenomas: Tubular adenoma, tubulovellous adenoma and adenoma vellous.
2. Non-epine neoplastic polyp: Leiomyomas, lipomas, neurofibromas and hemangiomas.
3. Hamartomatous polyp: Youth polyp, Peutz-Jeghers polyp.
4. inflammatory polyp: Benign lymphoid polyp. They're not usually evil.
5. Hyperplastic polyp: They have no evil potential. Its classification as a subgroup of serrated polyps can generate confusion because it also includes sesile serrated adenomas and traditional serrated adenomas which do have malignant potential

b) According to the form of growth

1. Paid polyp: They have an implantation stem of about 1.5 cm and imply less malignity because the cancerous degeneration takes longer to reach the subjecting base.
2. Sesile polyp: They have a wide implantation base (without stem) of about 2 cm and involve greater malignity because the cancer degeneration arrives before the base.

Most colorectal cancers arise from an adenoma, previously benign and later malignant. Adenomas are the most frequent benign tumors of the intestine, most of them located in the colon and rectum. The time required for the adenoma-carcinoma transformation to occur is over 5 years, with an average of 10-15 years.

Histology of Adenomatous Polyps

• Tubular adenoma: formed by epithelial tubules, is small and can be sesile or pediculate.
• Vellous adenoma: formed by digitiform or papillary processes constituted by connective tissue covered with epithelial cells. It is usually more voluminous than the tubular and sesile adenomas in most cases. The vellous adenoma, due to its histology and greater volume, is the one with the greatest potential of malignity.
• Mixed adenoma tubulo-vellous or mixed: that participates in the characteristics of both types.
• Served Adenoma: It corresponds to a polyp with hyperplastic areas and adenomatous areas, with greater malignant potential than pure adenoma.

Poor prognostic factors for an adenoma

Only adenomas are clearly premalignant, and only a minority develop into cancer. Early detection studies in the general population and autopsies have revealed that adenomatous polyps in the colon can be found in 30% of middle-aged or elderly people. Taking this prevalence and the known incidence of colorectal cancers into account, it appears that less than 1% of polyps become malignant. The factors that determine the malignant transformation of an adenoma are:

1. The adenoma or polyp size, in such a way that the greater the size will be the probability of cancer, being insignificant (less than 2%) in lesions less than 1.5 cm, intermediate (2 to 10%) in lesions of 1.5 to 2.5 cm in size and high (45%) in lesions greater than 2.5 cm.
2. The histologic type, so that the probability of transformation into a carcinoma is 40% in a hairy adenoma and 5% in a tubular adenoma.
3. La presence of dysplasia epithelial, which increases the likelihood that a polyp will curse. They are frequently observed in inflammatory bowel disease.
4. Clinical parameters: Advanced age, family history of polyposis, recidiva after local excision.
5. Morphological parameters: Size greater than 2 centimeters, multiple, hairy adenomas, evolution time.

For an adenomatous polyp to transform into a carcinoma, the activation of oncogenes by mutations that promote altered proliferation of the colonic mucosa is required, followed by the loss of genes that suppress tumor genesis.

Symptoms

• Most colon polyps are asymptomatic and are discovered casually during an exploration indicated for another reason.
• Some adenomas may bleeding: In less than 5% of patients with polyps you can find blood hidden in feces.
• If they are large and pedicure they can cause Pain or alterations of motility with diarrhea.
• Vellous adenoma can produce a lot of mucus that is eliminated in the form of false diarrhea. If the loss is continuous and abundant, it causes abundant loss of potassium, which generates hypokalemia, which is often added hyponatremia and hypochloremia.

Diagnosis

Polyps of the colon are usually detected by endoscopy (proctosigmoidoscopy or colonoscopy) or by opaque enema. After detecting an adenomatous polyp, the entire large intestine should be studied, since in one third of cases there are coexisting lesions. Colonoscopy should be repeated periodically, even if malignancy has not been previously demonstrated, because these patients have a 30-50% chance of developing another adenoma, and their risk of developing colorectal cancer is higher than average. A study conducted in the USA in the 1980s, called the National Polyp Study, suggests repeating the colonoscopy every 3 years.

Treatment

• It is currently considered that all types of polypectomy should be removed because they are potentially at risk, even though endoscopic polypectomy is not at risk, between 1-2% cases (mainly bleeding and/or colon perforation, sometimes requiring urgent surgery for resolution).
• Yeah. adenoma is less than 1 cmThey have a low risk of malignancy. If the polyp measures more than 2 cm it may have degenerated.
• Yeah. adenoma is greater than 1 cm, are removed via endoscopic (endoscopic polypectomy) those in which the size, situation and degree of malignancy permits. Endoanal resection techniques or transesfinterian back pathway will be used for those malignant vellous adenomas that have not exceeded the muscle layer. In tumors with signs of malignization located in middle and upper thirds, previous resection of the rectum will be made.

Prevention of colorectal cancer

Prevention and early detection of colorectal cancer is possible because most colon tumors form from adenomatous polyps. Removing polyps can lower a person's risk of getting cancer. Early diagnosis can reduce the number of colon cancer cases by promoting the detection and removal of polyps that can become cancerous, and can also reduce the death rate due to colorectal cancer by detecting the disease in its earliest stages, when it is highly curable.