What is acid reflux?

Barrett esophagus is suspected at endoscopy and is confirmed by biopsy and histological examination. The columnar epithelium of the stomach is reddish pink, and the junction between the glossy white squamous mucosa and the columnar mucosa (Z-line) is normally found at the lower end of the tubular esophagus, just above the proximal folds of a hiatal hernia, if present. In Barrett esophagus, the distal esophagus is lined with columnar epithelium, extending upward for a variable distance, often 3 to 10 cm, but occasionally involving most of the esophagus.The proximal margin may be horizontal, or there may be irregular, often tongue-shaped upward extensions of columnar mucosa. Some patients have pale islands of regenerative or residual squamous epithelium, whereas others have punched-out benign ulcers in the columnar area. Strictures and esophagitis may be seen at the new squamocolumnar junction. The endoscopist should especially look for evidence of adenocarcinoma, such as nodularity or masses.

The characteristic histological finding in Barrett esophagus is a distinctive specialized intestinal epithelium. This is a glandular epithelium with mucin-type cells and the distinguishing presence of goblet cells. These are easily seen on hematoxylin and eosin–stained sections and can be demonstrated more prominently in sections stained with Alcian blue. It occupies most or all of the columnar-lined area and is the type of epithelium in which adenocarcinoma arises. Other types of epithelia seen with Barrett esophagus include gastric fundic and cardia-type epithelia, but these alone do not make the diagnosis of Barrett esophagus, nor are they associated with adenocarcinoma.

Currently, there is some controversy over the classification of Barrett esophagus. The classical or long-segment Barrett esophagus requires at least 3 cm of esophagus to be lined with columnar epithelium. This is the best-studied subset of Barrett esophagus, with traditional demographic features and a definite increased risk of becoming adenocarcinoma. Short-segment Barrett esophagus refers to shorter lengths or tongues of columnar epithelium, less than 3 cm, in the distal esophagus, with intestinal metaplasia on biopsy. This entity is three to five times more common than the long-segment variant, but, based on anecdotal reports, the risk of cancer appears to be lower. Intestinal metaplasia at the esophagogastric junction refers to microscopic findings on biopsy but no visible columnar epithelium in the esophagus at endoscopy. This finding has been reported in 10% to 32% of biopsies from unselected patients, many of whom have no reflux symptoms. The percentage of woman and African Americans is also higher with this lesion than with either long- or short-segment Barrett esophagus. The cause is controversial; some investigators suggest that this is the earliest form of GERD, whereas others believe these changes are secondary to H pylori infection. Cancer risk is minimal, if it exists at all.