OCCULT PANCREATIC INSULINOMA: 111 INOCTREOTIDE RADIOGUIDED SURGERY. CASE REPORT AND REVIEW OF LITERATURE ON PRE AND INTRAOPERATIVE DIAGNOSIS.

Abstract

Introduction: pancreatic insulinoma is a small, rare neoplasm; its radical therapy is surgical enucleation or resection. Although clinical diagnosis is simple, instrumental and radiological localization is still difficult (occult insulinoma: 10-20%).

Material and methods: the authors present the case of a 71year-old patient suffering from relapsing vertigo syndrome, derangement and transient lypothymia after strong physical activity. ECG, encephalic and abdominal C.T., eco-colorDoppler of epiaortic vessels failed to identify any pathological features. Laboratory tests only revealed that basal glycemia was always lower than normal. Insulinoma was strongly suspected following the outcome of dosages of insulina and C-peptide in the serum and was confirmed after a supervised fast test (72 h). Once the biochemical diagnosis had been reached an abdominal eco, C.T., a selective and superselective angiography and ecoendoscopy were carried out to locate the tumor site but results were negative. Only somatostatinreceptor-scintigraphy with 111 In-octreotide detected a catchment area (diameter: 3 cm) to the right of the hypochondrium, anterior to the kidney and caudal to the left hepatic lobe.

Results: during laparotomy a hand-held gamma detecting probe (C-Trak) was used to detect in situ tumour binding of the radiolabelled octreotide and a neoplasm was identified and enucleated from the pancreatic head (diameter: 7 mm), undistinguishable from the surrounding parenchyma.

Postoperative signal checks of the surgical field and of the neoplasm revealed, in the first, the absence of captation and, in the second, maximal captation. Histological findings confirmed the nature of the neoplasm: an insulinoma with a ring pattern. Two years after surgery the patient is in good health, with no signs of relapse.

Conclusions: radioguided surgery with labelled octreotide makes it possible to pinpoint small insulinomas, locate occult neoplasm, verify the completeness of surgical excision in the field and in the surgical piece, by comparing the different captation of labelled octreotide and check neoplasm multicentricity and any metastases.