A polyp is a growth in a mucous membrane. A colon polyp forms in the surface lining of the membrane in the colon, but they can also develop elsewhere in the body such as nasal passages, mouth, uterus and genital area, and bladder. Most colon polyps are noncancerous. However, there are cases where the polyp continues to grow abnormally and become cancerous. There are two distinct colon polyp shapes and four different types of polyp. Read on and learn more about which ones are which, and which ones can be malignant (cancerous) and which are benign.

Pedunculated polyps

Shape 1 of colon polyps is the pedunculated polyp. These are raised growths, attached to the mucous membrane surface by a long peduncle, or stalk. Much like a mushroom: they are bulbous on top, with a stem. These kinds of polyps are easy to find as they intrude so much into the colon space, almost as if they were standing up. The structure of a pedunculated polyp will remain the same with small characteristic changes appearing, depending on what type of specific polyp it is. Tests are the only way to know which type you have.

colon polyp


Sessile polyps

Shape 2 of colon polyps is the sessile polyp. These polyps are harder to find because they lie flat on the surface of the mucous membrane. They do not have a stalk and are often overlooked in examinations, simply because they are more camouflaged than the pedunculated polyp. These polyps are more likely to become cancerous due to the fact they may stay on the lining for a longer period before diagnosis and treatment, plus they are harder to remove and usually require surgery.


Inflammatory colon polyp

An inflammatory colon polyp is mostly referred to as ‘false polyps' because they are usually benign and unlikely to become cancer. These growths are a manifestation of Inflammatory Bowel Disease (IBD) and are commonly found in the colon of someone suffering from the condition. Inflammatory polyps of the colon are also found in people with Chron's disease and ulcerative colitis. Out of all the colon polyp types, this is probably the least intrusive one. It would still need to be removed but the likelihood of it becoming cancer is very slim.


Hyperplastic polyp

One of the most common colon polyps is known as a hyperplastic polyp. Named because of its fast organic growth of abnormal tissue, the ‘hyper' rate at which the tissue mass grows cells result in the enlarged, or engorged polyp. Even though the steady growth is speedy, most of these polyps remain benign and have a very low risk of becoming cancerous. They are also often removed at the time of they are found. Hyperplastic growth can appear in other parts of the body, within organs and tissue, and if often confused with a benign tumor.

colon polyps


Adenomatous polyp

An adenoma is a glandular structure formed in tissue. Adenomatous colon polyps represent up to 70% of all colon polyps, but they can be benign or cancerous. Once an adenoma becomes cancerous, it is then referred to as an adenocarcinoma. The length of time it takes for the polyp to become cancerous is typically many years, and most of the time the patient will not even know it is there. This process is when the growth loses all its characteristics of normal cell structure and becomes a tumor.


Tubular Adenoma

A tubular adenoma is an adenoma, which has tubular features. This refers to the pattern the cells make under a microscope. A tubular adenoma has a different growth pattern to a villous adenoma. The way a tubular adenoma grows it is usually considered to be pre-malignant, but will most likely become malignant over time. Which is why it is best to get them out when they are still benign. If left untreated, they can turn into colon cancer and even progress to rectal cancer.

tubular colon polyp


Villous adenoma

A villous adenoma is the kind of polyp that is most likely to become cancer when left untreated, or undiscovered. It has been estimated that up to 30% of all villous adenoma colon polyps become cancerous. The villous adenoma has specific lumps and bumps protruding from it, much like a cauliflower. They are covered with columnar epithelial cells, which are the cells that line cavities, organs and blood vessels in the body. They can grow large and intrusive, and it is best to remove them as soon as possible from the lining of the colon.

adenoma colon polyp


Are colon polyps cancerous?

They way that colon polyps and adenomas are diagnosed as cancerous depends on many factors. First and foremost, the size and type are determined. Then the degree of dysphasia is measured, which means finding the amount of proliferated abnormal cells within the structure, and other deformation of the tissue mass. For example, a 1.5-centimeter tubular adenoma will have a 2% cancer risk, but a 3-centimeter villous adenoma has a 25% risk of becoming cancerous. To diagnose these cancers there will usually be a screening schedule to determine the rate of growth.


Symptoms of colon polyps

Colon polyps are sometimes tricky to find and diagnose; this is because they often don't have many symptoms. You can't see or feel them because of where they are located, but you may notice some changes in bowel movements such as constipation or diarrhea, dark or bright red stool, or blood in your stool, and some abdominal pain. These symptoms are common for other diseases and conditions as well, so they only way to know for sure, and the way colon polyps are usually discovered, is through a colorectal examination such as a colonoscopy, sigmoidoscopy, Barium Enema or a fecal occult stool test. If you do have any of these symptoms for more than one week, you should see your physician. If the tumors are large, it may obstruct the colon and bleeding from the anus.

symptoms colon polyp


Treatment for colon polyps

If you are over 50 or older, you are advised to have a colorectal screening. It is recommended that every polyp that is larger than one centimeter should be removed. This is so any cancerous polyps are caught before they cause further damage. These can be removed during a colonoscopy. The polyps are taken and examined in a lab to determine if they are cancerous or not. Larger polyps need to be removed by surgery, and if the cancer has been found, there are various ways to treat the disease depending on the location and extent of the cancer. Usually, this is with radiation therapy and chemotherapy.

surgery colon polyp


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