by Jason Wasserman MD PhD FRCPC
January 27, 2023
A tubulovillous adenoma (TVA) 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 tubulovillous adenomas are associated with an increased risk of developing a type of colon cancer called adenocarcinoma over time.
No, tubulovillous adenoma does not mean cancer. However, all tubulovillous adenomas are considered precancerous growths because they can turn into a type of colon cancer called adenocarcinoma over time.
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, tubulovillous adenomas are a type of polyp. However, not all polyps in the colon are tubulovillous adenomas. Other types of polyps in the colon include tubular adenomas, villous adenomas, and sessile serrated lesions.
The diagnosis of tubulovillous 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.
When examined under the microscope, the cells in parts of the tubulovillous adenoma connect together to form long, thin finger-like projections called villi. In other areas, the cells in the adenoma connect together to form 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.
All tubulovillous adenomas show an abnormal pattern of growth called dysplasia. Dysplasia is important because it is a precancerous change that can become cancerous over time. Pathologists divide dysplasia into two levels when examining a tubulovillous adenoma: low grade dysplasia and high grade dysplasia.
Low grade dysplasia is an early precancerous change seen in most tubulovillous adenomas. If left untreated, low grade dysplasia can change into high grade dysplasia or cancer over time. However, the overall risk is low.
High grade dysplasia is a more advanced precancerous change seen in a small number of tubulovillous adenomas. If left untreated, tubulovillous adenomas with high grade dysplasia can turn into a type of colon cancer called adenocarcinoma. If possible, all tubulovillous adenomas with high grade dysplasia should be removed completely.
A margin is any tissue that was cut by the surgeon in order to remove the tubulovillous 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 tubulovillous 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 tubulovillous 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.