Definition of Barrett's oesophagus.

Barrett's oesophagus is the eponym applied to the columnar epithelium-lined lower oesophagus. In 1976, Paull et al. described three types of columnar epithelia lining the distal oesophagus: a junctional or cardiac-type epithelium, a gastric fundic-type epithelium and a distinctive type of intestinal metaplasia referred to as specialized columnar epithelium. Even the normal oesophagus can be lined by 2 cm of columnar epithelium. To avoid the problem of false-positive diagnoses, arbitrary criteria for the extent of oesophageal columnar lining necessary to include patients in studies of Barrett's oesophagus were established in the early 1980s. The latter criteria require a circumferential segment of columnar lined epithelium of 2 or 3 cm in length. There are, however, a number of technical and conceptual problems related to this approach. The traditional definition excludes shorter segments and tongues of columnar lined epithelium. Only the specialized columnar epithelium defined by intestinal type goblet cells carries an inherent risk of malignancy. Therefore, a number of investigators currently define Barrett's oesophagus as any amount of columnar mucosa in the lower esophagus that has histologic evidence of goblet cells (highlighted in biopsies using the alcian blue pH 2.5 stain). Recently, short segments of specialized intestinal metaplasia in the distal oesophagus ("short segment Barrett's oesophagus") have attracted considerable attention. It has also become clear that intestinal metaplasia can occur at a normally located gastro-oesophageal junction. The etiology and clinical significance (in terms of possible relationship to the adenocarcinoma of the cardia) of this "intestinal metaplasia of the gastric cardia" and its potential relationship to Barrett's oesophagus are not yet completely understood.