Endocrine Abstracts

Malignant insulinoma is an extremely uncommon tumor (5–10% of insulinomas). It is accompanied by severe hypoglycemia and a short life expectancy (survival at 10 years <10%). Its clinical management is complex and constitutes a real therapeutic challenge. So far, the experience of radionuclide treatment in these tumors is scarce. We report the case of a 51-year-old woman diagnosed with pancreatic neuroendocrine tumor (pNET) in January 2013. Pre-surgical imaging study by abdominal CT scan showed a hypodense image in the tail of the pancreas with multiple liver metastases and large (up to 14 cm) ovarian masses. She underwent surgery on 09/01/2013 by exploratory laparotomy performing bilateral adnexectomy with pathological result of large cell neuroendocrine carcinoma (Ki-67 60%). The post-surgical [111In] DTPA-octreotide scintigraphy (Octreoscan) revealed hypercaptant lesions in the pancreatic tail, beginning treatment with lanreotide autogel 120 mg/28 days and sunitinib 37.5 mg/day, achieving a stabilization of the pancreatic and hepatic lesions. After tumor progression, she received six cycles of chemotherapy (cisplatin-etoposide) with partial response (50% size reduction) of the pancreatic lesion and stabilization of the liver metastases. After the 3rd cycle, she began to have severe and repeated hypoglycemic episodes with neuroglycopenic symptoms and frequent loss of consciousness even with seizures. Despite treatment with everolimus (10 mg/day for 3 months) and later with steroids (methylprednisolone, 32 mg/day), diazoxide (150 mg/day) and octreotide long-acting release (LAR) (30 mg/2 wk) the patient continued with frequent severe hypoglycemia (blood glucose 20 mg/dl, serum insulin 132 mU/ml and serum peptide C 18.7 ng/ml). On 21/07/2017, a first dose (177 mCi) of ¹⁷⁷Lu-DOTATATE was administered. After 10 days, the patient reported a clear clinical improvement, disappearing symptoms of hypoglycemia, showing an adequate control of capillary blood glucose throughout the day. In her last clinical visit in January 2018, after three doses of ¹⁷⁷Lu-DOTATATE (total dose 577 mCi), the patient continued without symptoms of hypoglycemia without the need to take diazoxide. The only treatment at this time was glucocorticoid replacement therapy and SSA (octreotide long-acting release LAR, 30 mg/2 wk). With this medication analytical study showed a blood glucose level of 115 mg/dl with normal serum insulin (20.3 mU/ml) and C-peptide (5 ng/ml) levels. In conclusion, ¹⁷⁷Lu-DOTATATE effectively and early controls severe hypoglycemia associated with malignant insulinoma. Therefore, we suggest its use in early stages of symptomatic disease not controlled with medication.