Table 1.

Clinical features of functional neuroendocrine tumors

Tumor type (alphabetical order)	Type of excess mediator(s) production	Signs and symptoms
Carcinoid	Chromogranin A, serotonin, histamine, kinins	Bronchoconstriction, cyanosis, diarrhea, flushing telangiectasia
Gastrinoma	Gastrin	Diarrhea, refractory GERD, severe peptic ulcer (Zollinger–Ellison syndrome)
Glucagonoma	Glucagon and enteroglucagon	Diarrhea, chronic necrolytic migratory erythema, secondary diabetes mellitus, stomatitis, unintentional weight loss
Insulinoma	Proinsulin, insulin	Confusion, hypoglycemia, sweating, weakness; improvement of hypoglycemic symptoms with glucose/carbohydrate intake
PPoma	Pancreatic polypeptide	Abdominal pain, jaundice, unintentional weight loss
Somatostatinoma	Somatostatin	Cholelithiasis, diarrhea, secondary diabetes mellitus, steatorrhea, unintentional weight loss
VIPoma	Vasointestinal peptide	Achlorhydria, hypokalemia, watery diarrhea (Verner–Morrison/WDHA syndrome)

Abbreviations: GERD, gastroesophageal reflux disease; PPoma, pancreatic polypeptidoma; VIPoma, vasoactive intestinal peptide-producing tumor; WDHA, watery diarrhea, hypokalemia, and achlorhydria.