Insulinoma

Insulinomas are rare pancreatic neuroendocrine neoplasms (panNENs - incidence of 1-3 cases per million per year). Most are solitary and do not show signs of malignant spread. Multiple synchronous or metachronous panNENs / insulinomas may occur in multiple endocrine neoplasia type 1 (MEN-1). The diagnosis of an insulinoma requires demonstration of inappropriately high insulin, proinsulin, or C-peptide levels for the prevailing hypoglycemia in a 72h fast. Localization of the tumor and exclusion or confirmation of metastatic disease by computed tomography is the preferred initial option followed by endoscopic ultrasonography (EUS) or MRI. Glucagon-like peptide receptor 1 (GLP-1R) receptor positron emission tomography (PET) CT is a most promising new localization technique, but regretfully not widely available yet. For single solitary tumors surgical excision is the treatment of choice. In malignant cases, debulking of the panNENs, including locoregional lymph nodes can be considered. If hyperinsulinemia and hypoglycemia persist, diazoxide with a thiazide diuretic relieves hypoglycemia. Liver metastases can be resected or treated by bland embolization, radioembolization (SIRT), radiofrequency ablation (RFA), microwave and cryoablation, high-intensity focused ultrasound (HIFU), laser, brachytherapy and irreversible electroporation (IRE) depending on local availability. In patients with unresectable low-grade metastatic malignant insulinomas, the long-acting somatostatin analog Lanreotide Autogel is the approved first-line therapy for control of tumor growth and sometimes control of hypoglycemia is achieved with this drug. If indicated, peptide receptor radiotherapy (PRRT) with radiolabeled somatostatin analogs, or Everolimus can be used for tumor, symptom and biochemical control. Malignant NENs can also be treated with cytotoxic chemotherapy regimens, particularly those with a high tumor grad