Barrett’s esophagus

Barrett’s esophagus is known to be a premalignant condition in patients with gastroesophageal reflux disease, and most adenocarcinomas of the distal esophagus have been shown to arise in Barrett’s tissue. Barrett’s esophagus is defined histologically by the presence of specialized columnar epithelium (SCE) with goblet cells. The columnar-lined lower esophagus (CLE) can be identified during standard upper endoscopy. SCE is often present in a patchy mosaic contribution within CLE and can be overlooked by random biopsies, resulting in biopsies of the cardia type of mucosa without goblet cells. However, it has been suggested that four-quadrant step biopsies within CLE should serve as the gold standard for diagnosing Barrett’s epithelium and Barrett’s-associated neoplastic changes. Endomicroscopy makes it possible to identify CLE macroscopically and identify goblet cells microscopically in the distal esophagus, allowing an immediate and reliable diagnosis of Barrett’s esophagus.

		Confocal Pattern Classification for Barrett's esophagus and associated neoplasias

In an endomicroscopic study (Kiesslich et al., Clin Gastroenterol Hepathol 2006) including 63 patients, different types of epithelial cell were distinguished and cellular and vascular changes were detected using fluorescein-guided endomicroscopy. A classification of confocal images for the diagnosis of Barrett’s epithelium and Barrett’s-associated neoplasias was developed on the basis of a comparison of the in vivo and conventional ex vivo histology (Table 1). The classification distinguishes between three types of epithelium (gastric epithelium; Barrett’s epithelium without neoplastic changes; and Barrett’s epithelium with neoplastic changes). Confocal imaging of the normal squamous epithelium of the esophagus demonstrated squamous cells at high resolution, showing capillaries (filled with red blood cells) within single papillae. It also became obvious that the number of papillae appears to increase after damage to the epithelium (e.g., in erosive esophagitis). It is possible to diagnose dilated intercellular spaces, which can be seen in patients with esophageal damage. Analysis of the Z-line showed the clear border between squamous and columnar-lined epithelium. Goblet cells, which are pathognomonic for Barrett’s epithelium, are easily identified. The mucin (MUC2) in goblet cells appears as dark spots within single cells of columnar-lined epithelium. The typical shape of Barrett’s epithelium was villous, differing from the cardiac epithelium. High-grade intraepithelial neoplasias or early cancers can be recognized by a distinct cell type in endomicroscopy. The highly irregular and polygonal cells have a rather black appearance, with irregular borders. In addition, an irregular epithelial cell layer with typical black cells and loss of a regular basal border was found to indicate high-grade intraepithelial neoplasia. The brightness of the lamina propria became heterogeneous due to the mixed vasculature of neoangiogenesis and leakage phenomena. In this study, 156 areas and 3012 images were reassessed in accordance with the confocal Barrett classification and compared with the targeted biopsies (411 biopsies). The comparison showed that Barrett’s esophagus can be predicted with the help of confocal endomicroscopy with a sensitivity of 98.1% and a specificity of 94.1%, respectively (accuracy 96.8%; positive predictive value 97.2 %; negative predictive value 96.0 %). Moreover, Barrett’s-associated neoplastic changes can be predicted with a sensitivity of 92.9% and a specificity of 98.4 %, respectively (accuracy 97.4 %; positive predictive value 92.9 %; negative predictive value 98.4 %).