[Precursors of gastric cancer : Dysplasia and adenoma].

Gastric cancer develops from preneoplastic and early neoplastic precursor lesions. In particular, the intestinal type according to the Lauren classification is driven by chronic inflammation and progresses via a chronic gastritis - atrophy/metaplasia - dysplasia - carcinoma sequence. Staging of the extent of atrophy (OLGA) or intestinal metaplasia (OLGIM) enables risk stratification and determines follow-up investigations according to the management of precancerous conditions and lesions in the stomach (MAPS) international guidelines. True adenomatous lesions are relatively rare in the stomach. Three major types need to be considered: the intestinal type (tubular, tubulovillous and villous), the foveolar type (with superficial gastric differentiation) and the pyloric gland adenoma (with deep gastric differentiation). The intestinal type is the most common and needs to be differentiated from nonneoplastic polypoid regenerative hyperplasia, but also from well-differentiated tubular adenocarcinoma.