Endocrine Abstracts

Background: Insulinoma is a rare tumour representing 1–2% of all pancreatic neoplasms and it is malignant in only 10% of cases. Locoregional invasion or metastases define malignancy, whereas dimension (> 2 cm), CK19 status, tumor staging and grading (Ki67 > 2%), and age of onset (> 50 years) can be considered elements of suspect.

Case presentation: We report a case of malignant insulinoma in a 80 year old woman presenting symptoms compatible with hypoglycemia. Low blood glucose levels (< 40 mg/dl) were documented during of these episodes. Symptoms regressed with food intake and intravenous glucose administration. No abnormality was detected in the biochemical evaluation. Prolong fasting test was performed, and the patient underwent symptomatic hypoglycemia at the 5th hour. Plasma glucose level was 39  mg/dl, insulin level 36.4  uIU/mL and C-peptide 9.28 ng/ml. Glucagon responce was measured 10 min. intervals, 85 mg/dl, 95 mg/dl and 113 mg/dl respectively. These results were suggestive of endogenous hyperinsulinemia. Magnetic resonance imaging revealed a invasive mass in the pancreatic tail location ~ 63 × 40 mm in size and multiple metastatic nodules in the the liver. Ga–68 DOTATATE PET-CT, which showed a lesion located in the pancreatic tail location and multıpl metastatic lesion in the liver, with a high somatostatin receptor density. Tru-cut biopsy made from liver lesions revealed the insulinoma tumour metastasis. Synaptophysin, pancytoceratine and chromogranin were positive. The histopathological diagnosis was suggestive of a neuroendocrine, grade-2 tumour (mitotic rate 1/10 HPF, KI-67 proliferative index 15%). Lanreotide 120 mg IM was started an every 28 days basis. The patient received 2 infusions of radiolabeled somatostatin analog lutetium (177LU) 8 weeks apart and denied any hypoglycemia. After the second administration of the lutetium, Ga–68 DOTATATE PET-CT had shown objective metabolic and radiologic response to treatment. Lutetium treatment was given as 8 cycles. Treatment of the patient with metabolic and radiological responses continues with lanreotide 90 mg/every 28 days.

Conclusions: We report a case of metastatic insulinoma treatment with somatostatin analog and Lutetium. Due to previous glycemic control reports and objective responses in unresectable cases, we decided to use Lutetium together with lanreotide. The patient’s hypoglycaemia improved immediately after treatment. Unresectable metastatic insulinomas may present as a major therapeutic challenge for the physician. Treatment with landreotide and Lutetium (177LU) seems to be effective in the management of severe, life-threatening, and refractory hypoglycemia associated with malignant insulinoma, as shown in the case presented here.