Intestinal phenotypes in pediatric gallbladder epithelium

The aim of this study was to characterize the physiologic expression of "intestinal" features in gallbladders of infants and children. The study group consisted of 56 pediatric (age, 2 weeks to 7 years) and 15 adult (15-25 years) patients who underwent incidental cholecystectomy during surgery for other lesions. All gallbladders examined were histologically unremarkable without inflammation, gallstones, or neoplasia. The presence of goblet cells and the expression of cytokeratin 7, cytokeratin 20, mucin core protein 2, and caudal-related homeobox protein 2 were examined. Intestinal features were frequently detected in the pediatric gallbladders: goblet cells in 34 cases (61%), cytokeratin 20 expression in 25 (45%), mucin core protein 2 expression in 32 (57%), and caudal-related homeobox protein 2 expression in 16 (29%). In contrast, none of these features was identified in adult gallbladders. The expression of mucin core protein 2 was mostly restricted to goblet cells in pediatric gallbladders, whereas cytokeratin 20 and caudal-related homeobox protein 2 were expressed in both goblet and nongoblet cells. Cytokeratin 7 was diffusely and consistently expressed in both pediatric and adult gallbladder epithelium including goblet cells. Intestinal features became less frequent with age and were scarce in children aged 6 to 7 years. Thus, goblet cells were identified in 14 (93%) of 15 children aged <1 year, together with the common expression of cytokeratin 20 (73%), mucin core protein 2 (93%), and caudal-related homeobox protein 2 (53%). In conclusion, intestinal features are physiologically present in gallbladder epithelium of children, particularly those aged <6 years. Intestinal metaplasia, as associated with cholangiopathy or carcinogenesis in adult patients, may represent an immature phenotype of biliary epithelium.