Esophageal dysplasia and adenocarcinoma: a study with double immunostaining for intestinal and gastric markers

Columnar lined esophagus is a complication of long term gastroesophageal reflux disease and the main precursor of esophageal adenocarcinoma. Incomplete intestinal metaplasia in reflux esophagitis represents one of the most important risk factors for neoplastic transformation through the metaplasia-dysplasia-adenocarcinoma sequence. However, recent studies suggest that cardiac type mucosa also shows molecular abnormalities which are similar to those of incomplete intestinal metaplasia. Immunohistochemically, three types of esophageal dysplasia and adenocarcinoma are recognized: adenomatous-intestinal, hybrid/mixed and foveolar gastric types. We are interested in the phenotypes of these dysplasias and adenocarcinomas, especially in the possible relationship between them. For this reason, we evaluated the immunohistochemical expression of intestinal and gastric markers in a series of 30 cases of esophageal high-grade dysplasia (high-grade intraepithelial neoplasia) and of 70 adenocarcinomas. For immunohistochemical classification, we used double immunohistochemical reactions CDX2/MUC5AC and CDX2/MUC6, respectively. In cases of incomplete intestinal metaplasia, hybrid/mixed high-grade dysplasia and hybrid/mixed adenocarcinoma, we found the expression of gastric mucins MUC5AC and MUC6 only in cells with intestinal differentiation (with nuclear positivity for CDX2). The double immunostaining excluded the presence of the cells with "pure" foveolar gastric phenotype in hybrid lesions. Thus, the hybrid category actually represents the intestinal type dysplasia/adenocarcinoma (which is known to have a better prognosis than the foveolar gastric type). Keywords: immunohistochemistry - double immunostaining - reflux esophagitis - Barrett esophagus - esophageal dysplasia - esophageal adenocarcinoma.