Role of EUS in the preoperative localization of insulinomas compared with spiral CT

Background: Preoperative radiologic localization of insulinomas often fails because of the small size of these tumors. Endoscopic ultrasound (EUS) can localize insulinomas In up to 80% of the cases. The aim of this study was to compare EUS and computed tomography (CT) diagnostic accuracy for insulinomas, Methods: We reviewed medical records from 12 patients (10 women) with a biochemical diagnosis of hypoglycemia and hyperinsulinism from 1 university hospital and 1 community hospital. A diagnosis of insulinoma was ultimately made in all cases and before surgery the patients underwent abdominal US, spiral CT and EUS in an attempt to precisely localize the tumor. Surgery was considered the standard for tumor localization. Results: Ten tumors were benign (83.3%) and 2 were malignant (16.7%). The overall sensitivity of EUS in identifying insulinomas was 83.3% compared with 16.7% for CT. Tumors not detected by EUS had a mean size of 0.75 cm, EUS-guided fine-needle aspiration was possible in only 3 patients, with a positive cytologic diagnosis in 2 (66.6%). Tumors located in the head end body of the pancreas were identified by EUS in all patients, but those located in the tail were diagnosed in only 50% of the cases. Conclusions: EUS is superior to spiral CT and should replace it for the detection of pancreatic insulinomas, EUS identification depends on the site and size of the tumor.