An adenoma is a type of polyp, or a small cluster of cells that forms on the lining of your colon.

When doctors look at an adenoma under a microscope, they can see small differences between it and your colon’s normal lining. Adenomas typically grow very slowly and look like a small mushroom with a stalk.

Tubular adenomas are the most common type. They’re considered benign, or noncancerous. But sometimes cancer can develop in an adenoma if it isn’t removed. If adenomas become cancerous, they’re referred to as adenocarcinomas.

Less than 10 percent of all adenomas will turn into cancer, but more than 95 percent of colon cancers develop from adenomas.

Read on to learn more about how doctors treat tubular adenomas.

There are two types of adenomas: tubular and villous. These are categorized by their growth patterns.

Sometimes doctors refer to polyps as being tubulovillous adenomas because they have features of both types.

Most small adenomas are tubular, while larger ones are typically villous. An adenoma is considered small when it’s less than 1/2 inch in size.

Villous adenomas are more likely to turn cancerous.

There are several other types of polyps, including:

  • hyperplastic
  • inflammatory
  • hamartomatous
  • serrated

When polyps in your colon are removed, they’re sent to a pathology lab to be studied.

A specialized doctor, known as a pathologist, will send your healthcare provider a pathology report that gives information about each of the samples that were taken.

The report will tell you the type of polyp you have and how much it looks like cancer under a microscope. Dysplasia is a term used to describe precancerous or abnormal cells.

Polyps that don’t look much like cancer are referred to as having low-grade dysplasia. If your adenoma looks more abnormal and more like cancer, it’s described as having high-grade dysplasia.

Many times, adenomas don’t cause any symptoms at all and are only detected when they show up during a colonoscopy.

Some people will have symptoms, which may include:

Your doctor will probably remove any adenomas you may have because they can turn into cancer.

Doctors can take out a tubular adenoma with a retractable wire loop that’s placed through the scope that’s used during a colonoscopy. Sometimes small polyps can be destroyed with a special device that delivers heat. If an adenoma is very large, you might need to have surgery to remove it.

Typically, all adenomas should be completely removed. If you had a biopsy but your doctor didn’t completely take out your polyp, you’ll need to discuss what to do next.

Once you have an adenoma, you’ll need to have frequent follow-up testing to make sure you don’t develop any more polyps.

Your healthcare provider will probably recommend that you have another colonoscopy screening:

  • within six months if you had a large adenoma or one that had to be taken out in fragments
  • within three years if you had more than 10 adenomas
  • in three years if you had an adenoma 0.4 inches or larger, if you had more than two adenomas, or if you had certain types of adenomas
  • in 5 to 10 years if you had just one or two small adenomas

Talk to your doctor about your specific situation and when you might need to have another colonoscopy.

If you’ve had an adenoma, you could be at risk for developing another one. Your chances of developing colorectal cancer may also be higher.

It’s important to see your doctor regularly and have all recommended screening procedures.