By Jason Wasserman MD PhD FRCPC
January 26, 2023

What is a duodenal adenoma?

A duodenal adenoma is a non-cancerous type of polyp that starts in a part of the small intestine called the duodenum. It is considered a precancerous condition because it can turn into a type of cancer called adenocarcinoma over time. Another name for this type of polyp is non-ampullary adenoma.

What causes a duodenal adenoma?

Just over half of all 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 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 duodenal adenoma?

Small duodenal adenomas do not cause any symptoms and are usually found incidentally when an examination called an upper endoscopy is performed. Larger adenomas that block the duodenum can cause symptoms such as abdominal pain, bloating, vomiting, and nausea.

How common are duodenal adenomas?

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 FAP.

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

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

Duodenal adenoma with low grade dysplasia

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

Duodenal adenoma with high grade dysplasia

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

How is this diagnosis made?

The diagnosis of 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