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 Zollinger-Ellison syndrome (gastrinoma) glucagonoma insulinoma somatostatinoma VIPoma non-functioning tumor Glucagonoma Neoplasm of α-islet cells Presentation symptoms rash (necrolytic migratory erthema) chelitis weight loss diabetes mellitus venous thrombosis neuropsychiatric physical exam hyperglycemia Treatment surgery medical octreotide (somatostatin analogue) Insulinoma Neoplasm of β-islet cells most common islet cell tumor Association with MEN I Presentation symptoms mental status alterations physical exam hypoglycemia Evaluation serology ↑ insulin ↑ C-peptide important to distinguish patients who are injecting themselves with insulin (would be low) Treatment surgery Somatostatinoma Neoplasm of δ-islet cells somatostatin is normally an inhibitor of most GI hormones Presentation symptoms achlorhydria blockage of gastin release cholelithiasis blockage of CCK release steatorrhea blockage of secretin release diabetes mellitus blockage of GIP release Treatment surgery medical combination chemotherapy 5-fluorouracil streptozotocin alkylating agent that targets cells arising from Islets of Langerhans VIPoma Neoplasm that produces ectopic vasoactive intestinal peptide (VIP) normal functions of VIP activates cAMP intestinal epithelial cells results in secretory diarrhea vasodilation inhbition of gastric acid secretion stimulation of intestinal secretion smooth muscle cell relaxation (lower esophageal sphincter) Presentation symptoms facial flushing secretory diarrhea (also called pancreatic cholera) achlorhydria Evaluation serology hypokalemia normal anion gap metabolic acidosis resembles labs of other secretory diarrheas hypercalcemia Treatment surgery medical octreotide Nonfunctioning tumors Do not present with hormonal syndrome