Neuroendocrine neoplasm Somatostatinoma A somatostatinoma secretes somatostatin, which typically inhibits numerous gastrointestinal and endocrine functions. Clinically, this condition often presents with a classic triad of diabetes mellitus, cholelithiasis, and steatorrhea, resulting from hormonal suppression. On noncontrast CT, somatostatinomas typically appear isodense relative to pancreatic parenchyma. Endoscopic ultrasound is highly sensitive and specific for detecting pancreatic neuroendocrine neoplasms, including lesions smaller than 5 mm. Somatostatin receptor-based positron emission tomography (PET) using appropriate radiolabeled ligands demonstrates excellent sensitivity and specificity for tumor localization and staging. Somatostatinoma is a rare, functional neuroendocrine tumor (NET) that primarily arises in the pancreas and duodenum, characterized by excessive production of somatostatin.