Localization of an Insulinoma by CT-Angiography

ABSTRACT

Insulinomas are the most common type of islet cell tumor. Generally, these tumors are benign (90%), intrapancreatic, solitary, and small (measuring less than 2 cm), and they occur throughout the head, body, and tail of the pancreas with equal frequency. The methods for diagnosing an insulinoma involve whipples triad and biochemical test by a monitored 72-hour test. The diagnosis is obtained by blood for glucose and insulin, C-peptide samples taken every 4 to 6 hours during the test, particularly when symptoms develop, and calculation of the insulin to glucose ratio. Preoperative radiographic localization of islet cell tumors in patients with insulinomas is important to remove the tumor adequately. A 43-year-old man with dizziness, sweating, and loss of consciousness twice in a period of 2 years was hospitalized with clinical suspicion of an insulinoma. The findings of computed tomography,and transabdominal and endoscopic ultrasonography were all negative. Transhepatic venous sampling for a pancreatic hormone assay showed a sudden increase in the insulin level in the proximity of the head of the pancreas, however, this was not localized correctly. We report a case where insulin was found in the tail of the pancreas, as confirmed by CT-angiography , and we present a review of literature.