A 61 years old male with Z-E syndrome is reported. He presented gastrointestinal bleeding, abdominal pain, slightly elevated gastrin and hypoglycemia. He underwent total gastrectomy, a non-resectable tumor of the tail of the pancreas with liver metastasis were found. A biopsy of the liver metastasis and the gastric mucosa were reviewed under the light and the transmission electronic microscopes. The gastric mucosa showed abundant parietal cells. The metastatic hepatic tissue was poorly differentiated under the light microscope and the electron micrographs revealed tissue resembling pancreatic islands of Langerhans with granules in the cytoplasm, this means that the neoplasm originated from APUD cells.