Preoperative localization of insulinomas is not necessary

Insulinomas are infrequent but are important to recognize and surgically remove. Several diagnostic tests have been used to increase the chances of operative success. The value of preoperative testing for insulinomas is the subject of this review.

All patients treated at the Cleveland Clinic for insulinoma between 1985 and 1995 were retrospectively reviewed. All patients had biochemical evidence of primary hyperinsulinemia.

There were 21 patients, 10 men and 11 women, with a median age of 58 years. Eighteen patients (85%) had a single insulinoma, two patients (10%) had multiple insulinomas, and one patient (5%) had nesidioblastosis. In addition, two patients (10%) had malignant insulinoma. A total of 13 patients (62%) had successful preoperative localization of their tumors, and all of these were found during exploration either by the surgeon (12 patients) or by intraoperative ultrasonography (1 patient). The remaining eight patients (38%) did not have their lesion localized by preoperative tests. In seven patients these tumors were found at operation, three by the surgeon and four by intraoperative ultrasonography. One patient failed preoperative and intraoperative localization and was later diagnosed with nesidioblastosis. Enucleation was performed in 13 patients and distal pancreatectomy in 7; the patient with nesidioblastosis had a negative laparotomy and a subsequent distal pancreatectomy. The mortality and morbidity rates were 0% and 14%, respectively. Only two patients, including the patient with nesidioblastosis, remained symptomatic after operation.

The diagnosis of an insulinoma does not require extensive localization studies before operation. The combination of surgical exploration and intraoperative ultrasonography identified more than 90% of insulinomas. When technically feasible, enudeation is curative and can be accomplished with low morbidity.