Intestinal phenotypic expression of gastric depressed adenomas and the surrounding mucosa.

Background: Gastric depressed adenomas (DAs) have been reported to be more aggressive than nondepressed ones. To clarify any differences among them, we investigated the intestinal phenotypic expression of DAs and the surrounding mucosa.

Methods: Fifty DAs resected surgically or endoscopically were studied. Forty-two nondepressed adenomas (Non-DAs) were selected as controls. According to the classification of intestinal metaplasia, the phenotypes of the adenomas and surrounding mucosa were classified into four categories: complete intestinal type (I/Com-type), incomplete intestinal type (I/In-type), gastric type (G-type), and unclassified type (U-type), based on a combination of the expression of the antibodies CD10 (small-intestinal brush border), MUC2 (intestinal goblet cells) and HGM (gastric foveolar epithelium).

Results: I/In-type adenomas were frequently observed among DAs (60%), whereas I/Com-type adenomas were frequently seen in Non-DAs (52%). The incidence of phenotypes was significantly different among DAs and Non-DAs. Intestinal metaplasia was present in the surrounding mucosa of more than 90% of both DAs and Non-DAs. Surrounding mucosa of I/In-type was also frequently observed in DAs, as was that of I/Com-type in Non-DAs. The expression of p53 in DAs (8%) was higher than that in Non-DAs (5%). p53-positive adenomas were present only among the I/Com-type and I/In-type adenomas, while G-type and U-type adenomas showed no p53 positivity.

Conclusions: Both DAs and their surrounding mucosa appear to have an unstable status, because they possess a hybrid phenotype of I/In-type more commonly than Non-DAs. Such instability could be considered a risk factor for neoplastic potential and, therefore, DAs should be followed carefully.