Tubular adenoma of the colon and rectum

by Jason Wasserman MD PhD FRCPC
January 26, 2023

What is a tubular adenoma?

A tubular adenoma (TA) is a noncancerous type of polyp that can develop anywhere in the colon and rectum. It develops from the cells that cover the inside surface of these tissues. If left untreated, all tubular adenomas are associated with an increased risk of developing a type of colon cancer called adenocarcinoma over time.

Does tubular adenoma mean cancer?

No, tubular adenoma does not mean cancer. However, all tubular adenomas are considered precancerous growths because they can turn into a type of colon cancer called adenocarcinoma over time.

What is the difference between a tubular adenoma and a polyp?

In pathology, the term polyp is used to describe any growth that sticks out from the surface of a tissue. Because of the way they grow, tubular adenomas are a type of polyp. However, not all polyps in the colon are tubular adenomas. Other types of polyps in the colon include tubulovillous adenoma, villous adenoma, and sessile serrated lesions.

How is the diagnosis of tubular adenoma made?

The diagnosis of tubular adenoma can only be made after part, or all of the adenoma is removed and the tissue is examined under the microscope by a pathologist. The adenoma may be removed in one piece or in multiple pieces.

What does a tubular adenoma look like under the microscope?

When examined under the microscope, the cells in a tubular adenoma connect together to form long, thin tube-shaped glands. The nuclei (the part of the cell that holds the genetic material) of the cells in the adenoma are also larger and hyperchromatic (darker) compared to the cells normally found on the inside surface of the colon.

tubular adenoma
The glands of a tubular adenoma are seen on the right side of this image. Normal glands are on the left.

What does dysplasia mean and why is it important in a tubular adenoma?

All tubular adenomas show an abnormal pattern of growth called dysplasia. Dysplasia is important because it is a precancerous change that can become cancerous over time. When examining a tubular adenoma, pathologists divide dysplasia into two levels: low grade dysplasia and high grade dysplasia.

Tubular adenoma with low grade dysplasia

Low grade dysplasia is an early precancerous change seen in most tubular adenomas. If left untreated, low grade dysplasia can change into high grade dysplasia or cancer over time. However, the overall risk is low.

Tubular adenoma with high grade dysplasia

High grade dysplasia is a more advanced precancerous change seen in a small number of tubular adenomas. If left untreated, tubular adenomas with high grade dysplasia can turn into a type of colon cancer called adenocarcinoma. If possible, all tubular adenomas with high grade dysplasia should be removed completely.

What is a margin and why is it important?

A margin is any tissue that was cut by the surgeon in order to remove the tubular adenoma from your body. Dysplasia at the cut edge of the tissue means that the abnormal tissue may not have been completely removed from the body.

Some tubular adenomas grow on a piece of tissue called a stalk and the adenoma is removed by cutting the stalk. In these cases, the margin is the part of the stalk that is cut. However, most tubular adenomas are removed and sent to pathology as multiple pieces (fragments) of tissue. In these cases, it may not be possible for your pathologist to determine which piece is the real margin and the changes seen at the margin will not be described in your report.

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