Taking as their starting point the observation of a pancreatic malignant endocrine neoplasm with mixed production of serotonin and pancreatic polypeptide, the authors go on to review the literature on the diagnosis and treatment of pancreatic apudomas. The possibility of performing an extempore intraoperative histological examination makes it possible to obtain a correct diagnosis of endocrine neoplasm and thus to proceed with surgery which could not be contemplated in adenocarcinomatous forms at an equivalent stage. Chemotherapy may then provide additional therapeutic possibilities, using specific markers for malignancies of the APUD system in order to detect possible recurrences.