Diagnosis of non-Zollinger-Ellison syndrome, non-carcinoid syndrome, enteropancreatic neuroendocrine tumours.

The diagnosis of entero-neuropancreatic tumours different from Zollinger-Ellison syndrome and carcinoid syndrome require an high index of suspicion and even when they are associated to virulent syndromes such as VIPoma or insulinoma syndrome the mean delay in diagnosis is of 4 years. Symptomatic hypoglycaemia due to inappropriate insulin release from insulinoma and watery diarrhoea leading to dehydration caused by elevated circulant vaso-intestinal peptide levels are present in the 90% and 100% of the patients at presentation of the respective syndrome. Somatostatinoma syndrome has a far more subtle presentation and it tends to present much later during the disease course. The diagnosis is based on the presence of gallstones, diabetes, weight loss, diarrhoea and steatorrhoea. Growth hormone releasing factor neuroendocrine tumours (GRFoma) present with acromegaly and account for less than 2% of the acromegalic patients in which the growth hormone is from an ectopic source located in the pancreas. The Cushing's syndrome diagnosis due to rare ectopic neuroendocrine tumour adrenocorticotropic hormone secretion can be made only with selective angiography, whereas non-functional and pancreatic polypeptide producing neuroendocrine tumours (PPoma) present without any symptoms. Finally, multiple endocrine neoplasia type one occurs more commonly with somatostatinoma or GRFoma, conversely patients with multiple endocrine neoplasia type one can develop insulinoma (20%) or PPoma (60%).