Multilayered epithelium in Barrett's esophagus

Expression of CDX2 and MUC2 in Barrett's mucosa

Barrett's mucosa is a risk factor for esophageal adenocarcinoma and should be detected at an early stage. It is defined by the presence of columnar epithelium with goblet cells in the lower esophagus, but histologic diagnosis can be uncertain in the absence of distinct goblet cells. We investigated 55 biopsies from 48 patients with endoscopically plain Barrett's esophagus and performed immunohistochemistry for CDX2 and MUC2. In addition, alcian blue (pH 2,5)/PAS staining was done. In histologically unequivocal Barrett's mucosa, nuclear expression of CDX2 in goblet cells and many columnar cells, as well as cytoplasmic positivity for MUC2 in goblet cells, could be observed. Alcian blue (pH 2,5)/PAS stained acidic mucins in goblet cells and in some non-goblet columnar cells. In six cases, no definite Barrett's mucosa was present, and no expression of MUC2 could be observed. In these biopsies, there was granular cytoplasmic and/or focal nuclear staining for CDX2 in non-goblet columnar epithelial cells, indicating their intestinal differentiation. We suggest that this peculiar mucosa is the precursor of unequivocal Barrett's mucosa and would designate it early Barrett's mucosa. Alcian blue for acidic mucins is inconsistent in this epithelium and does not reliably indicate early intestinal differentiation.

The genesis of Barrett esophagus: has a histologic transition from gastroesophageal reflux disease-damaged epithelium to columnar metaplasia ever been seen in humans?

Has a histologic transition from gastroesophageal reflux disease-damaged epithelium to columnar metaplasia ever been seen in humans? The answer to this question seems to be that it has but that we either do not readily recognize it or it is not readily recognizable with regular light microscopy. There are at least 3 possible mechanisms for the genesis of Barrett esophagus. The first is ulceration at the gastroesophageal junction with subsequent repair by an epithelium that differentiates into Barrett epithelium. The second is metaplasia through multilayered epithelium. The third is creeping columnar metaplasia at the Z-line proximally followed by intestinalization. These 3 hypotheses may not be mutually exclusive, and all may be operative, depending on the local circumstances, amount of inflammation, erosion, ulcers, healing, acid and alkaline reflux, and use of proton pump inhibitors. Any of the epithelial types involved could be stable and not progress. They might even be reversible, which may also in part explain the mosaic of epithelial types that typify Barrett esophagus, and may be modified by any of the molecular mechanisms that turn protein transcription on and off (eg, promoter methylation, mutations). These mechanisms ultimately may also be involved in the genesis of neoplastic transformation.

Ciliated Surface in the Esophagogastric Junction Zone

We have previously reported squamous metaplasia-like change at the esophagogastric junction (EGJ). In the present study, we examined these lesions histologically and by immunohistochemistry and electron microscopy. Samples of EGJ mucosa, 3 cm long and comprising 1.5-cm long portions of both columnar and squamous mucosa, were obtained from 43 esophagectomy resection specimens. Squamous metaplasia-like change was observed in 21 (49%) of the 43 cases. The squamous metaplasia-like change was generally positive with immunohistochemical stains for tubulin and cytokeratins (CKs) 4, 7, 8, 13, and 18, and was generally negative with stains for CKs 10, 14, and 20. This pattern of immunoreactivity is very similar to that of bronchial mucosa. Also, many cilia were detected at the apices of the cells by electron microscopy in 5 (31%) of the 16 cases that were able to be examined. Therefore, squamous metaplasia-like change at the EGJ has both a similar appearance and a similar immunohistochemical profile to respiratory bronchial epithelium. These findings may suggest that squamous metaplasia-like change at the EGJ is not a precursor of Barrett's mucosa but rather is a form of pseudostratified metaplasia.