Somatostatinoma
Summary
A rare neuroendocrine tumor (usually pancreatic delta-cell origin) that secretes somatostatin, producing the classic triad of diabetes, cholelithiasis, and steatorrhea. Somatostatin inhibits insulin, CCK, and pancreatic enzyme secretion.
Detail
Somatostatin is the universal 'inhibitory' hormone: it suppresses insulin, glucagon, gastrin, secretin, CCK, GH, TSH, and pancreatic exocrine secretion. A somatostatinoma therefore causes hyperglycemia (low insulin), gallstones (decreased CCK -> gallbladder hypomotility), and steatorrhea/achlorhydria (decreased pancreatic enzymes and acid). Most arise in the pancreas (head) or duodenum and may be associated with MEN1 and neurofibromatosis type 1 (especially periampullary). Diagnosis: elevated plasma somatostatin; imaging with somatostatin receptor scintigraphy (octreoscan) or DOTATATE PET. Treatment: surgical resection; octreotide for symptom control is paradoxically used. Boards triad: 'diabetes + gallstones + steatorrhea.'
Sources
- First Aid for USMLE Step 1 2024
- Robbins Basic Pathology 10th ed
- Pathoma
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