Nonampullary duodenal adenoma

by Jason Wasserman MD PhD FRCPC
August 1, 2024

Background:

A nonampullary duodenal adenoma is a non-cancerous polyp that starts in the duodenum of the small intestine. It is considered a precancerous condition because it can turn into a type of cancer called adenocarcinoma over time. Nonampullary duodenal adenomas are uncommon, being found in less than 1% of people examined by upper endoscopy. However, the rate is much higher in patients with familial adenomatous polyposis syndrome (FAP).

What does nonampullary mean?

This type of adenoma is described as “nonampullary” when it is found in a part of the duodenum away from a structure called the ampulla. The ampulla (also known as the ampulla of Vater) is a small opening that connects the common bile duct and the main pancreatic duct to the duodenum. It is through the ampulla that bile (from the gallbladder) and secretions (from the pancreas) flow into the duodenum.

What causes a nonampullary duodenal adenoma?

Just over half of all nonampullary duodenal adenomas occur in patients with familial adenomatous polyposis (FAP) syndrome. In these patients, adenomas are caused by an APC gene mutation leading to increased cell growth and division. Just under half of all nonampullary duodenal adenomas occur in patients without FAP, and at present, doctors do not know what causes these adenomas to develop.

What are the symptoms of a nonampullary duodenal adenoma?

Small nonampullary duodenal adenomas do not cause symptoms and are usually found incidentally during an upper endoscopy. Larger adenomas that block the duodenum can cause symptoms such as abdominal pain, bloating, vomiting, and nausea.

Dysplasia in a nonampullar duodenal adenoma

All nonampullary duodenal 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 nonampullary duodenal adenoma, pathologists divide dysplasia into two levels: low grade dysplasia and high grade dysplasia.

Nonampullary duodenal adenoma with low grade dysplasia

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

Nonampullary duodenal adenoma with high grade dysplasia

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

How is this diagnosis made?

The diagnosis of nonampullary duodenal 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.

Other helpful resources

Information on Familial Adenomatous Polyposis syndrome from Cancer.net