Metastatic insulinoma in an adult patient with underlying nesidioblastosis

Abstract

To report a case of metastatic insulinoma presenting 11 yr after enucleation of an isolated insulinoma, and 5 yr after distal pancreatectomy for nesidioblastosis. We present the clinical, laboratory, radiological and pathological findings in a 34 yr-old-man with recurrent hypoglycemia. The pertinent literature is reviewed. A 34- yr-old man presented in 1992 with symptoms of recurrent hypoglycemia. Laboratory and imaging findings were consistent with insulinoma. After enucleation of the tumor, his symptoms resolved. In 1998 hypoglycemia recurred and biochemical work-up was consistent with endogenous hyperinsulinism. Imaging for recurrent or metastatic insulinoma revealed no mass. He underwent a distal pancreatectomy and pathology revealed islet cell hyperplasia, or nesidioblastosis. However, the patient reported minimal symptomatic improvement. He was started on diazoxide but was poorly compliant and ate frequently to avoid hypoglycemic symptoms. In 2003 he presented with hypoglycemia-induced seizure activity. Imaging showed hepatic and pulmonary lesions, but no pancreatic mass. An octreotide scan revealed increased hepatic uptake and fine needle aspiration of a liver lesion confirmed metastatic insulinoma. Arterial-stimulation venous sampling revealed increased insulin output from the liver and normal insulin output from the pancreas. After failure of medical therapy, radiofrequency ablation of hepatic lesions was performed with subsequent improvement in clinical symptoms. The patient was discharged on a low dose of dexamethasone. Although this patient had nesidioblastosis, his recurrent hyperinsulinism was most likely secondary to metastatic insulinoma. Radiofrequency ablation was successfully used for palliative purposes in managing metastatic insulinoma refractory to medical therapy.