Neuroendocrine tumors of the stomach. Pathogenesis, classification and clinical correlations

Neuroendocrine tumors of the stomach are classified into four types mostly on the basis of their pathological associations: 1) carcinoid type I, associated with atrophic corporal gastritis, 2) carcinoid type I, associated with multiple endocrine neoplasia type 1, 3) carcinoid type III, sporadic, and 4) neuroendocrine carcinoma. The first two types develop through a histologically recognizable sequence hyperplasia dysplasia - neoplasia. Their pathogenesis depends on the combined action of promoting agents, mostly hypergastrinemia, and of transforming agents,the role of which is currently under investigation. Their prognosis is generally favourable in sharp contrast with that of the other two types of tumors, which is usually poor. The pathogenesis and the precursor lesions of the latter neoplasms have not been clarified yet.