Metaplasia of the distal esophageal mucosa from squamous cell to columnar type cell; associated with impaired functioning of the esophageal body and lower esophageal sphincter. Cause is gastroesophageal reflux disease. Condition is considered premalignant and is now thought to be at least partially reversible with fundoplication. Indication for esophageal resection includes high-grade dysplasia on random biopsy taken during 2 separate endoscopies.