Non-goblet cell population of Barrett's esophagus: an immunohistochemical demonstration of intestinal differentiation.

Barrett's esophagus develops with the following 2 distinct types of lining mucosa: with and without specialized intestinal metaplasia (SIM). Goblet cells found only in SIM areas identify an intestinal phenotype, recognized as the histological hallmark diagnosing Barrett's metaplasia, and selecting high-risk patients for endoscopic surveillance. The columnar non-goblet cells are the major component of the heterogeneous Barrett's metaplastic cell population and are present in areas either with or without SIM. Their significance in the differentiation of columnar-lined esophagus, and their relationship to malignancy, is still unclear. This immunohistochemical study used two markers of enterocytic differentiation, to explore the intestinal phenotype of the non-goblet cell population of Barrett's epithelium and Barrett's-associated adenocarcinoma cells. Sucrase-isomaltase (SI) and dipeptidilpeptidase IV (DPP) immunoexpression was assessed in paraffin-embedded samples of 12 surgical specimens containing Barrett's esophageal mucosa in association with adenocarcinoma/high grade dysplasia. Ileal mucosa and mucosa from normal gastric and esophageal segments of the surgical specimen were used as positive and negative controls, respectively. SI and DPP were expressed by the neoplastic cells and the columnar non-goblet, being negative in goblet cells. The localization of the enzymes was predominantly apical for SI and cytoplasmatic for DPP. There was immunoreactivity for SI in 58.3% of the carcinomas and in 66.6% of Barrett's mucosa, with equal frequency in areas with and without SIM. DPP was identified in 66.6% of the carcinomas, in 50% of the cases of Barrett's metaplasia with SIM, and in 75% of those without SIM. The columnar non-goblet cell components of Barrett's metaplasia contain small intestine enzymes in the areas either with or without SIM, which suggests that they identify an "incomplete form" of intestinal metaplasia. The demonstration that the two enzymes, SI and DPP, are produced by the columnar non-goblet cell metaplastic population and by the neoplastic cells of the associated adenocarcinoma, indicates that, in addition to the goblet cells, the non-goblet elements may also be involved in the malignant transformation of Barrett's esophagus.