[Gastric metaplasia and dysplasia. Relationship to cancer]

The histogenesis of gastric cancer is still hypothetical. A major difficulty in attempting to define the different steps of gastric carcinogenesis is the great confusion of terminology concerning the epithelial abnormalities, such as metaplasia and dysplasia. The author proposes the following definitions. Metaplasia is the transformation of a normal tissue into another normal tissue with different structure and functions. Hyperplasia is characterized by an increased number of cells but without modification of tissue organization. Neoplasia is a tissue neoformation linked to an excessive cell proliferation. Dysplasia, in gastric pathology, is an acquired abnormality of cell multiplication implicating evolution toward malignity but with phenotype expression confined only to the epithelium. Based on strict morphological criteria, the diagnosis of dysplasia leads to the diagnosis of intra-epithelial carcinoma, which is important for the preventive treatment of gastric cancer.