Barrett’s esophagus

What is Barrett’s esophagus?

Barrett’s esophagus is a non-cancerous condition where the cells that line the inside of the esophagus change to look like the cells that normally line the inside of the small bowel. Barrett’s esophagus is associated with long-standing acid reflux disease. People with Barrett’s esophagus are at increased risk for developing a type of cancer in the esophagus called adenocarcinoma.

For most patient’s the risk of developing cancer after a diagnosis of Barrett’s esophagus is low. The presence of dysplasia, a type of abnormal cell growth, in Barrett’s esophagus increases the risk of cancer and your pathologist will carefully examine the tissue for any evidence of dysplasia (see Dysplasia below).

The esophagus

The esophagus is a long hollow tube that starts at the back of your throat and ends at the top of your stomach. Swallowed food travels down the esophagus into the stomach. The stomach is filled with a strong acid that helps your body break down food. The inner surface of the esophagus is lined by specialized squamous cells that form a barrier to protect the inside of the esophagus. This thin tissue barrier is called the epithelium.

normal esophagus histology

What causes Barrett’s esophagus?

Barrett’s esophagus is caused by long-standing acid reflux disease (this condition is also called “GERD”). When acid from the stomach enters the esophagus it damages the squamous cells that line the esophagus. Pathologists describe this as reflux esophagitis. Over time, the injured squamous cells are replaced by a type of epithelium normally found in the small intestine. This type of epithelium is made up of cells that are designed to protect tissue from the strong acids in the stomach. The change from squamous epithelium to small intestinal epithelium is an example of intestinal metaplasia.

How do pathologists make this diagnosis?​

Barrett’s esophagus is almost always diagnosed first on a biopsy. The biopsy is usually performed because the patient has symptoms consistent with acid reflux disease. The diagnosis may also be made on a resection specimen such as an endoscopic mucosal resection.

Under the microscope, your pathologist will see intestinal-type cells covering the inside of the esophagus.  In particular, your pathologist will look for a specialized type of cell called a goblet cell to make the diagnosis of Barrett’s esophagus. Goblet cells are large round cells that appear blue when examined under the microscope because they are full of a substance called mucin.

Dysplasia

Barrett’s esophagus that has been present for many years increases the risk for developing a change called dysplasia. Dysplasia is a word pathologists use to describe an abnormal pattern of growth that can lead to cancer over time. Not all tissues with dysplasia will turn into cancer and most tissues go through other changes before there is any evidence of cancer. Because of this risk, your pathologist will carefully examine your tissue sample for dysplasia and will include it in your pathology report if it is seen.

The earliest type of dysplasia is called low-grade dysplasia. The cells in low-grade dysplasia are darker and larger than normal cells. In some cases, the cells become even more abnormal and change to high-grade dysplasia. The cells in high-grade dysplasia look very similar to cancer cells but they are only seen in epithelium on the inner surface of the esophagus.

Although Barrett’s esophagus is considered a non-cancerous disease, the presence of dysplasia, in particular high-grade dysplasia, increases the risk that cancer in the esophagus called adenocarcinoma will develop in the future. For this reason, Barrett’s esophagus with dysplasia is considered a pre-cancerous or precursor disease.

Margins

A margin is normal tissue that surrounds an area of abnormal tissue and is removed with the abnormal tissue at the time of surgery. When a part of the esophagus is removed to treat Barrett’s esophagus, the surgeon will try to remove a small amount of normal esophagus (or sometimes stomach) to ensure that no abnormal tissue is left behind. High-grade dysplasia close to or at the cut edge of the tissue is associated with a higher risk of the disease coming back in the future.

Margins are not reported on biopsy specimens.

by Shaheed Hakim, MD FRCPC, updated December 11, 2020
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