ABSTRACT
Most of the digestive tract "APUDomas" originated in cells of the pancreatic islets (islets of Langerhans). The islets of Langerhans consist of aproximately one million clusters of cells dispersed among the pancreatic acinar cells. The various islets cells are believed to arise from the neural crest and along with other secretory cells belong to a family of cells designated of the APUD (amine precursor uptake and decarboxylation) series. On the basis of histochemical, ultrastructural and immunofluorescent techniques as well as the hormonal secretory products the islet cells as recognized as consisting of five distinct types: Alpha, Beta, Delta, f and enterochromaffin. Hyperinsulinemia resorting in hypoglycemia is the major clinical manifestation of insulin-producing islets cell tumors (insulinomas). This tumors may be either begin or malignant, the later representing up to 15 percent of the total. They may occur in any part of the gland, but over 60 percent occur in the body and tail of the pancreas. The diagnosis is usually made by finding an abnormally low plasma glucose concentration and an elevated (inappropiate) plasma insulin in the fasting state; but it may be necessary to fast the pacient for 72 hours. In rare instances hypoglycemia may be associated with a normal plasma insulin concentration. In such circunstances the insulin/glucose ratio may be helpful; a ratio in excess of 0.30 is indicative of hyperinsulinism. Once the diagnosis of insulinoma has been made, the tumor should be excised surgically. Gastrinomas (Zollinger-Ellison syndrome are non-beta-cell islet cell tumors which secrete excessive amounts of gastrin. The hallmarks of the Zollinger-Ellison syndrome are recurrent and intractable duodena ulcers and diarrhea. In a patient in whom gastrinoma is suspected provocative testing may be necessary to establish the diagnosis