Endocrine Abstracts

Insulinoma, a rare neuroendocrine tumor (NET), is benign in more than 90% of cases. We present a review of patients diagnosed with insulinoma at our Department.

Methods: Retrospective review of clinical records of patients diagnosed with insulinoma between 2011 and 2016.

Results: Six female patients were diagnosed with insulinoma (age at presentation 30–66, follow-up: 0.25–3.25 years). Episodes of sweating, palpitations, tremor, confusion, visual disturbances and weight gain were present in five patients from 2 months to 5 years before diagnosis. There was no familial history or clinical findings of hereditary tumor syndromes. The 72-h fast test confirmed endogenous hyperinsulinism at 4–12 h of fast. Abdominal CT: pancreatic lesion in four patients (14–25 mm). Endoscopic ultrasound done in four patients revealed pancreatic nodule; three performed cytology/biopsy compatible with pancreatic neuroendocrine tumor (pNET). Five patients underwent surgery: two tumor enucleation, three central and distal pancreatectomy with left hepatectomy and splenectomy in 1 of these. Histopathology: well differentiated pNET G1(two patients) and G2 (three patients). Two patients had lymph node involvement and one of them liver metastases. Among five surgically treated patients: four did not have recurrence of hypoglycemia and the one with liver metastases was treated with octreotide and deceased 2 years after diagnosis. The sixth patient had undergone central and distal pancreatectomy with splenectomy 5 years earlier due to pNET without diagnosis of insulinoma at that time and presented us with large hepatic metastases and hypoglycemia. Octreotide and peptide receptor radionucleide therapy (DOTA-TATE) were started due to hepatic hyperfixation in PET-68Ga-DOTANOC.

Discussion: In this group there was a high prevalence of malignancy, which is unusual. Time elapsed from onset of symptoms to diagnosis was highly variable. The natural history of malignant insulinoma is difficult to predict, however uncontrolled hypoglycemia, liver tumor burden exceeding 30% of liver volume, morphologic progression and Ki67 >10–20% are factors of poor prognosis.