Neuroendocrine tumours of the pancreas can secrete numerous peptides, leadi
ng to various recognizable clinical syndromes. The secretion of pancreatic
polypeptide has been used as a marker for neuroendocrine tumours but is con
sidered to be a biologically inert peptide. A 37-year-old woman had watery
diarrhea syndrome from pancreatic polypeptide hyperplasia. Only 2 other rep
orted cases in the literature have described pancreatic polypeptide hyperpl
asia; however, this is the first reported case in which the patient was suc
cessfully treated by surgical resection, with a 2-year follow-up. This repo
rt and review of the literature illustrate that pancreatic polypeptide hype
rsecretion may present as a clinical endocrinopathy.