Inflammatory diseases of the esophagus include several clinical conditions. The most common of these is gastroesophageal reflux disease (GERD), related to gastroesophageal reflux. Other causes include radiation, infections, medications, eosinophilic and lymphocytic esophagitis. One of the most important complications of GERD is Barrett’s esophagus, defined as a metaplastic conversion of the distal normal esophageal squamous mucosa (for at least 1 cm above the gastroesophageal junction) to intestinal columnar epithelium. This condition is a complication of untreated long-term GERD, because chronic acid exposure damages the esophageal squamous cells, causing their replacement with mucus-secreting cells.