GI Radiology > Pancreas > Neoplastic > Islet Cell

Pancreatic Islet Cell Tumors


Endocrine tumors include insulinomas, gastrinomas (Zollinger-Ellison syndrome), glucagonomas, VIPomas (Verner-Morrison syndrome), and somatostatinomas among others. While most insulinomas are benign, most gastinomas, glucagonomas, VIPomas, and somatostatinomas are malignant. Endocrine tumors of the pancreas are occasionally associated with other syndromes, including von-Hippel-Lindau disease (CNS hemangioma, renal cell carcinoma, adenomas and cysts of liver/kidney/pancreas, and islet cell tumors, ), and multiple endocrine neoplasia (MEN; pituitary, parathyroid, and pancreatic neoplasms).

Initial diagnosis of pancreatic endocrine tumors is based on specific symptoms, followed by immunoassay detection of a particular hormone. Imaging serves to localize the tumor. These tumors are less difficult to diagnose because of their hypervascular nature. The tumors appear as hyperdense masses on contrast-enhanced CT. Calcifications are more frequently seen in islet cell tumors than in ductal adenocarcinoma.

Insulinoma:

Insulinomas are the most common islet cell tumors, and occur most frequently in females over 40 years of age. More than 90% of insulinomas are benign. On US, inuslinomas appear as hypoechoic masses which are well demarcated from surrounding parenchyma. Most are smaller than 2 cm in diameter. EUS and intraoperative US are most sensitive for localization. CT is also highly accurate in the diagnosis of insulinomas. They appear as hyperattentuating tumors. The optimal treatment of insulinomas is surgical resection.

Gastrinoma:

Gastrinomas (Zollinger-Ellison syndrome) may be single or multiple; 60% are malignant. Most occur in men over 40 years of age. US and CT have limited roles in the diagnosis of primary tumors because the tumors are too small to be seen and may be ectopic. Ninety percent of extrapancreatic tumors are in the "gastrinoma triangle." (This "triangle" is bounded by the junction of the cystic and common bile duct superiorly, the second and third portion of the duodenum inferiorly, and the neck/body junction of the pancreas medially.) Barium studies and endoscopy may show ulcerations in the stomach, duodenum and jejunum. Octreotide scanning (somatostatin receptor scintigraphy) is commonly used for diagnosis of gastrinomas.


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