Diagnostic usefulness of radiolabeled pentetreotide scintigraphy and therapeutic efficiency of octreotide in a case of insulinoma.

Although the functional diagnosis of insulinoma is quite easy, its topographic diagnosis still constitutes a major challenge since conventional radiological techniques, e.g. ultrasonography, computed tomography and even selective angiography, fail to recognize the tumor in numbers of insulinomas. We report an observation of a benign insulinoma in an 81-year-old woman that escaped detection by ultrasonography and CT but was later localized by both endoscopic ultrasonography and somatostatin receptor scintigraphy. It illustrates the usefulness of such recent imaging techniques for the localization of islet cell tumors that escaped detection by ultrasonography and CT. Moreover, in our elderly patient who refused surgical intervention, hypoglycemia was corrected by octreotide administration emphasizing the predictive value of 111In-pentetreotide scintigraphy on the subsequent response to octreotide therapy in patients in whom the optimal treatment (surgical resection) is not possible.