Diagnosis and staging of islet cell tumors of the pancreas.

Pancreatic endocrine tumors arise from the amine precursor uptake and decarboxylation (APUD) cells of the pancreas and behave in a different fashion both biologically and clinically from pancreatic adenocarcinoma. Gastrinomas and insulinomas are the two most common pancreatic endocrine tumors. Unlike pancreatic adenocarcinoma, in which tumor stage, resectability, and prognosis are determined by the tumor, nodes, and metastasis (TNM) classification, the prognosis of pancreatic endocrine tumors is determined by the presence of liver but not regional lymph node metastasis. This review focuses predominantly on the different diagnostic tools available to the clinician and the relative merits of each modality. The sensitivities of computed tomography, magnetic resonance imaging, somatostatin receptor scintigraphy, endoscopic ultrasound, and angiography with venous sampling for diagnosing islet cell tumors are compared. A diagnostic algorithm for the management of these tumors is provided at the end of the discussion.