Snapshot A 50-year-old woman presents to her primary care physician complaining of prolonged episodes of watery diarrhea, fatigue, and muscle weakness. Laboratory results demonstrate that she is hypokalemic with a normal anion gap metabolic acidosis. Fasting VIP plasma levels confirmed the diagnosis of a VIPoma (islet cell tumor) and octreotide was started for treatment. Introduction May involve any cell type in the endocrine pancreas login to view 6 more bullets Glucagonoma Neoplasm of α-islet cells Presentation login to view 9 more bullets Treatment login to view 3 more bullets Insulinoma Neoplasm of β-islet cells login to view 1 more bullet Association with MEN I Presentation login to view 4 more bullets Evaluation login to view 4 more bullets Treatment login to view 1 more bullet Somatostatinoma Neoplasm of δ-islet cells login to view 1 more bullet Presentation login to view 9 more bullets Treatment login to view 6 more bullets VIPoma Neoplasm that produces ectopic vasoactive intestinal peptide (VIP) login to view 6 more bullets Presentation login to view 4 more bullets Evaluation login to view 5 more bullets Treatment login to view 3 more bullets Nonfunctioning tumors Do not present with hormonal syndrome