Differential diagnosis of malignant gastric tumors. A pathological appraisal with reference to locally advanced gastric carcinoma.

Locally advanced carcinomas are considered for comparison with non-neoplastic entities and other gastric and non-gastric tumor types. How can primary gastric carcinomas be pathologically distinguished from mimics and metastatic carcinomas? And carcinomas of the cardia from Barrett adenocarcinomas? And undifferentiated gastric carcinomas from other undifferentiated neoplasms? To answer these questions, topographic, morphologic and immunohistochemical distinctive features are illustrated. Moreover, a pathological "excursus" on the most frequent neoplasms of the stomach is provided along with epidemiological data concerning the incidence, survival and mortality rates of gastric carcinomas in Italy in the 1990s. Pathologic aspects and macro-microscopic appearances of carcinomas are described according to the most recent classification systems. A brief commentary is given on the new TNM staging formulation for gastric carcinomas. A correct pathological diagnosis of gastric carcinoma can be made in the vast majority of cases; however, some diagnostic uncertainties still exist in individual cases.