Intraoperative gamma probe detection of insulinoma in an elderly patient with pancreatic cystic lesions.

Insulinoma is a rare endocrine tumour in the elderly. We report the case of an 81-year-old woman suffering from grand mal seizures. Insulinoma was suspected because plasma glucose and insulin levels were 1.5 mmol/l and 80.4 pmol/l, respectively. A pancreatic computerized tomography (CT) scan, magnetic resonance imaging (MRI) and arteriography were normal but (111)In-DTPA-octreotide scintigraphy detected a hotspot in the pancreatic tail. Intraoperative pancreatic ultrasonography and palpation were non-contributory due to multiple pancreatic cysts and nodular lesions. However, a gamma-detecting probe localized a small tumour, labelled preoperatively with (111)In-DTPA-octreotide. Intraoperative insulin measurements in portal venous blood confirmed the successful removal of an insulinoma that was 6 mm in diameter histologically. Pancreatic cystic lesions increase with age and make the intraoperative localization of the insulinoma difficult. Intraoperative gamma probe detection of the tumour labelled with (111)In-DTPA-octreotide might therefore constitute a useful surgical tool.