<unk>  is a condition in which there is an abnormal (metaplastic) change in the mucosal cells lining the lower portion of the<unk> , from stratified squamous epithelium to simple columnar epithelium with interspersed goblet cells that are normally present only in the small intestine and large intestine. This change is considered to be a premalignant condition because it is associated with a high incidence of further transition to esophageal adenocarcinoma, an often-deadly cancer. The main cause of<unk>  is thought to be an adaptation to chronic acid exposure from reflux esophagitis.<unk>  is diagnosed by endoscopy: observing the characteristic appearance of this condition by direct inspection of the lower<unk> ; followed by microscopic examination of tissue from the affected area obtained from biopsy. The cells of<unk>  are classified into four categories: nondysplastic, low-grade dysplasia, high-grade dysplasia, and frank carcinoma. High-grade dysplasia and early stages of adenocarcinoma may be treated by endoscopic resection or radiofrequency ablation. Later stages of adenocarcinoma may be treated with surgical resection or palliation. Those with nondysplastic or low-grade dysplasia are managed by annual observation with endoscopy, or treatment with radiofrequency ablation. In high-grade dysplasia, the risk of developing cancer might be at 10% per patient-year or greater. The incidence of esophageal adenocarcinoma has increased substantially in the Western world in recent years. The condition is found in 5–15% of patients who seek medical care for heartburn (gastroesophageal reflux disease, or GERD), although a large subgroup of patients with<unk>  are asymptomatic. The condition is named after surgeon Norman<unk>  (1903–1979) even though the condition was originally described by Philip Rowland Allison in 1946.
Barrett's esophagus
Nutcracker esophagus
Herpes esophagitis
Zenker's diverticulum
Esophageal candidiasis
Lymphocytic esophagitis
Esophageal achalasia
Eosinophilic esophagitis