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 ce lls found only in SIM areas identify an intestinal phenotype, recognized as the histological hallmark diagnosing Barrett's metaplasia, and selecting h igh-risk patients for endoscopic surveillance. The columnar non-goblet cell s are the major component of the heterogeneous Barrett's metaplastic cell p opulation and are present in areas either with or without SIM. Their signif icance in the differentiation of columnar-lined esophagus, and their relati onship to malignancy is still unclear. This immunohistochemical study used two markers of enterocytic differentiation, to explore the intestinal pheno type of the non-goblet cell population of Barrett's epithelium and Barrett' s-associated adenocarcinoma cells. Sucrase-isomaltase (SI) and dipeptidilpe ptidase IV (DPP) immunoexpression was assessed in paraffin-embedded samples of 12 surgical specimens containing Barrett's esophageal mucosa in associa tion with adenocarcinoma:high grade dysplasia. heal mucosa and mucosa from normal gastric and esophageal segments of the surgical specimen were used a s positive and negative controls, respectively. SI and DPP were expressed b y the neoplastic cells and the columnar non-goblet, being negative in goble t cells. The localization of the enzymes was predominantly apical for SI an d 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 conta in small intestine enzymes in the areas either with or without SIM, which s uggests that they identify an "incomplete form" of intestinal metaplasia. T he demonstration that the two enzymes, SI and DPP, are produced by the colu mnar non-goblet cell metaplastic population and by the neoplastic cells of the associated adenocarcinoma, indicates that, in addition to the goblet ce lls, the non-goblet elements may also be involved in the malignant transfor mation of Barrett's esophagus. Copyright (C) 1999 by W.B. Saunders Company.