[Gastric differentiated stomach adenocarcinoma]

Gastric carcinomas are classified histogenetically into diffuse and differentiated types. The latter are often referred to as intestinal-type carcinomas and are believed to originate from intestinal metaplasia. However, histogenetic studies on smaller and initial lesions of the differentiated adenocarcinoma do not support this. From phenotypical expressions of neoplastic lesions arising in hyperplastic polyps of the stomach we first proposed an entity of gastric-type adenocarcinomas, which has been widely accepted. Our recent mucin and immunohistochemical investigations reveal that most smaller adenocarcinomas retain gastric-type differentiation and that those of the exclusively intestinal phenotype are rather rare. On the other hand, most adenomas are strongly and extensively positive for intestinal marker, indicating that the adenoma-carcinoma sequence is not a common event in the stomach carcinogenesis. Other studies show that the expression of intestinal mucin or carbohydrate antigen as expressed in intestinal metaplasia is manifested more extensively in carcinoma cells in larger tumors. It is suggested that intestinalization of tumor cells is a time-dependent phenomenon. Differential gene abnormalities between gastric- and intestinal-type carcinomas of the stomach are discussed, regarding their histogenesis and progression.