Neuroendocrine Tumors of the Stomach: Gastric Apudomas

Anatomo-clinical studies of the neuroendocrine tumors of the stomach only can be well completed with a view of the basic characteristics of the elements of the so-called neuroendocrine system or gastrointestinal APUD system. Therefore, these gastric neoplasias cannot be studied in isolation because they are derived from a special line of endocrine cells that have many common biochemical bonds which are often involved in the clinical behavior of the tumor. These cells are called “APUD” for their biochemical and morphological characteristics, and their tumors as “apudomas.” APUD cells store amines and regulatory peptides and are dispersed throughout the body and concentrated mainly in the digestive tract. Other names used for tumors of the same cell line, namely, “carcinoids,” “endocrine tumors,” and “neuroendocrine tumors,” are not yet very well defined, although they are ostensibly used. The gastric apudomas do not escape of the basic rules of behavior of their counterparts of other sites of the digestive tract. Nevertheless, most of them present peculiar pathogenetic and pathophysiological characteristics whose knowledge is important to better understand the patient with this type of lesion.