Case Presentation: Insulinoma is a rare tumor that originates in the beta cells of the pancreas with an incidence of 1-4 cases/million persons/year. Less than 10% of insulinomas are malignant and represent a treatment challenge despite the development of new therapeutic approaches in the last decade. A 28 year old female with no past medical presented with a 9 month history of recurrent syncope, diaphoresis, light-headedness and fatigue. She first noticed the symptoms during her 6th month of gestation. Her blood glucose during these episodes was in the range of 30-40 mg/dl and was thought to be due to her pregnancy. Postpartum she continued to experience recurrent symptomatic hypoglycemia for which she saw an endocrinologist. He performed laboratory tests which were consistent with insulinoma. She was started on Diaxozide for symptom control, but continued to be symptomatic and was admitted to our hospital after a syncopal episode secondary to hypoglycemia. Her physical examination revealed a morbidly obese female with a BMI of 46 with otherwise normal examination. Her labs showed an elevated fasting insulin level at 565.7 mU/l, elevated random insulin level at 322 mU/L, Pro-insulin at 567.5 pmol/l and C- peptide at 17.9 ng/ml. MRI abdomen/pelvis revealed multiple hyper and hypodense lesions in the liver. An endoscopic ultrasound (EUS) found an 8×12 mm round, hypoechoic mass in the body of the pancreas; An EUS guided biopsy showed an epithelial chromogranin positive neoplasm. An octreotide scan showed mild to moderate uptake in numerous hepatic lesions. The patient was started on continuous infusion of D40W titrated to blood glucose (BG) levels above 100. We incrementally added decadron, diaxozide and octreotide to prevent hypoglycemia with little success in maintaining normoglycemia. She underwent a resection of the pancreatic lesion and six liver wedges. Histopathology from all sites was consistent with stage IV, Grade 2 malignant insulinoma based on Ki67 labeling index (25% in this case). Post surgically her glycemia only improved slightly, but still requiring D40W, diaxozide and decadron which we were able to discontinue after switching octreotide to pasireotide. She also underwent a radioembolization of both hepatic lobes with Yttrium 90 to control her liver metastasis. Patient was discharged on everolimus and pasireotide with the goal of liver transplant as a curative approach. At her 4 week follow up visit, she reported no episodes of hypoglycemia at home.
Discussion: In the literature octreotide is the medication of choice to control glycemia in patients with insulinomas. However, in our case the commencement of Pasireotide is what made the difference in the management of her BG levels which has been reported only twice in the literature so far.
Conclusions: It is very important to consider, as illustrated in this case, alternative therapies like pasireotide, a Somastotatin analogue with a 40-fold increased affinity to Somatostatin receptors 5 (sst 5) which lead to a decrease in insulin secretion and therefore, less hypoglycemia compared with octreotide in patients with insulinoma.