Intestinalization of gastric signet ring cell carcinomas with progression.

Recent developments in mucin histochemistry and immunohistochemistry have made reliable determination of the gastric and intestinal phenotypes of gastric carcinoma cells possible. Phenotypic expression changes from gastric epithelial cell type to intestinal epithelial cell type with the growth of gastric tumours in experimental animals. We studied cell differentiation in gastric signet ring cell carcinomas with progression in 203 surgically obtained specimens. The results showed that the proportion of gastric phenotype carcinomas, in which over 90% of the tissue consists of gastric epithelial cell type cells, decreases with the depth of invasion. The proportion of mixed phenotype carcinomas (between 10% and 90% of the tissue made up of gastric and/or intestinal epithelial cell type cells) increases. The intestinal phenotype (over 90% intestinal epithelial cell type carcinoma cells) was found in four carcinomas (about 2%) involving the serosa. No clear relationship was evident between phenotypic expression of carcinoma cells and the degree of intestinal metaplasia of the surrounding mucosa. Progression of gastric signet ring cell carcinomas is associated with a phenotypic shift from gastric to intestinal type expression.