Copyright © 2006 by Indian Society of Gastroenterology Background: Insulinomas are rare tumors that are usually benign, single and curable by simple surgical excision. They can present problems in diagnosis and localization. Study design: Retrospective analysis of patients with insulinoma managed during a 13- year period (1992-2005) at a tertiary-level institution. Results: 31 patients (mean age 38.4 [SD 13.3] years; 16 men) presented with hypoglycemic symptoms for 4.6 (5.5) years. In 22 (71%) patients, the lesion was successfully localized pre-operatively. Of various pre- operative localization techniques, CT angiography (5/ 6; 83%), intra-arterial digital subtraction angiography (11/17; 65%), dual-phase CT (8/14; 57%), and con- ventional MRI (4/13; 31%) had high rates of success- ful tumor localization. Intra-operative palpation and ultrasonography also had localization success rates (22/30 [76%], and 11/12 [92%], respectively); each identified one lesion that the other procedure did not localize. Of the 30 patients who underwent surgery, 28 had solitary tumor. Conclusion: Pre-operative in- vestigations to localize insulinoma are helpful despite the availability of intra-operative ultrasound. Dual-phase CT should be the non-invasive investigation of first choice. [Indian J Gastroenterol 2006;25:244-247] I nsulinomas are rare tumors that occur in about 1 in 250,000 persons. 1 They are often very small at presentation because of the potent effects of insulin secreted. 2 Though functional and almost exclusively localized to the pancreas, they are often difficult to diagnose and to localize. Symptomatic hypoglycemic episodes are often non-specific, go unrecognized and are occasionally mistaken for seizures or psychiatric disorders for several years. 3,4 There have been reports of long-standing insulinoma with marked adaptation to extreme hypoglycemia with near-normal plasma insulin levels. 5 Nearly 80% of these tumors are less than 2 cm in size and may not be easily seen on pre-operative imaging using CT, ultrasonography (US) or MRI. 1,2 In addition, their identification at the time of sur- gery, except with the aid of intra-operative ultra- sonography (IOUS), may be difficult because of their intra-parenchymal location and small size. About 10% of all insulinomas are malignant (with metastases) and 10% are multiple, with 50% of the latter being associated with the multiple endocrine neoplasia syn- drome-1 (MEN-1). 6 There are few reports of insulinoma from In- dia. 7,8 We present a retrospective analysis of patients with insulinoma evaluated at a tertiary-care center. Methods Medical records of patients with insulinoma seen in the period 1992-2005 were retrieved from the hospital’s medical records department and the records of the Departments of Endocrinology, Gastro-intestinal Sur- gery and Radiology. From these, data on clinical and diagnostic features, localization and surgical outcome were extracted. Pre-operative localization of tumor was attempted using a combination of radiological techniques avail- able at the time of diagnosis, including trans-abdominal US, conventional contrast-enhanced CT scan (CECT till 2000), dual-phase CECT (since 1996), magnetic resonance imaging (MRI), conventional pancreatic arteriography (prior to 1994) and selective pancre- atic arteriography (since 1994), namely, intra-arterial digital subtraction angiography (IADSA) with or without CECT (CT angiography till 2000). Subjects under- went surgery wherein lesions were identified based on a combination of pre-operative localization, intra- operative palpation of the pancreas and IOUS (since 2000). Results Clinical characteristics Thirty-four patients with insulinoma (16 men) had been diagnosed over the 13-year study period. De- tails of three patients, including one with malignant insulinoma and another associated with parathyroid adenoma, were not available. All patients had pre- sented with fasting hypoglycemia and fulfilled Whipple’s triad to suspect a diagnosis of insulinoma. The diagnosis had been confirmed by demonstration of inappropriately elevated plasma insulin levels dur- ing an episode of spontaneous hypoglycemia or pro- Insulinoma: diagnosis and surgical treatment. Retrospective analysis of 31 cases Viveka P Jyotsna, Neil Rangel, Sujoy Pal,* Ashu Seith,** Peush Sahni,* A C Ammini Departments of Endocrinology and Metabolism, *Gastro-intestinal Surgery and **Radiology, All India Institute of Medical Sciences, New Delhi 110 029 Original Article