Review on novel concepts of columnar lined esophagus.

Background: Columnar lined esophagus (CLE) is a marker for gastroesophageal reflux and associates with an increased cancer risk among those with Barrett's esophagus. Recent studies fostered the development of integrated CLE concepts.

Methods: Using PubMed, we conducted a review of studies on novel histopathological concepts of nondysplastic CLE.

Results: Two histopathological concepts-the squamo-oxyntic gap (SOG) and the dilated distal esophagus (DDE), currently model our novel understanding of CLE. As a consequence of reflux, SOG interposes between the squamous lined esophagus and the oxyntic mucosa of the proximal stomach. Thus the SOG describes the histopathology of CLE within the tubular esophagus and the DDE, which is known to develop at the cost of a shortened lower esophageal sphincter and foster increased acid gastric reflux. Histopathological studies of the lower end of the esophagus indicate, that the DDE is reflux damaged, dilated, gastric type folds forming esophagus and cannot be differentiated from proximal stomach by endoscopy. While the endoscopically visible squamocolumnar junction (SCJ) defines the proximal limit of the SOG, the assessment of the distal limit requires the histopathology of measured multilevel biopsies. Within the SOG, CLE types distribute along a distinct zonation with intestinal metaplasia (IM; Barrett's esophagus) and/or cardiac mucosa (CM) at the SCJ and oxyntocardiac mucosa (OCM) within the distal portion of the SOG. The zonation follows the pH-gradient across the distal esophagus. Diagnosis of SOG and DDE includes endoscopy, histopathology of measured multi-level biopsies from the distal esophagus, function, and radiologic tests. CM and OCM do not require treatment and are surveilled in 5 year intervals, unless they associate with life quality impairing symptoms, which demand medical or surgical therapy. In the presence of an increased cancer risk profile, it is justified to consider radiofrequency ablation (RFA) of IM within clinical studies in order to prevent the progression to dysplasia and cancer. Dysplasia justifies RFA ± endoscopic resection.

Conclusions: SOG and DDE represent novel concepts fusing the morphological and functional aspects of CLE. Future studies should examine the impact of SOG and DDE for monitoring and management of gastroesophageal reflux disease (GERD).