Successful management of a sporadic pancreatic insulinoma by endoscopic ultrasound-guided radiofrequency ablation

A 70-year-old woman presented with an 18-month history of recurrent episodes of dizziness that were alleviated by sugary drinks. During one of these episodes, a low blood glucose of 1.6 mmol/L was noted. Her past medical history included atrial fibrillation and severe chronic obstructive pulmonary disease (COPD), necessitating long-term oxygen therapy. Given the high index of suspicion of spontaneous hypoglycemia, further investigations commenced with a supervised 72-hour fast. This confirmed symptomatic hyperinsulinemic hypoglycemia: serum glucose of 1.8 mmol/L (normal range 3 – 7.8), insulin 17.3 milliunits/L, and C-peptide 2418 pmol/L at 34 hours. The serum sulphonylurea screen was negative. A computed tomography (CT) scan revealed an 18-mm enhancing lesion in the uncinate consistent with a neuroendocrine tumor and this was confirmed by an endoscopic ultrasound with fine needle aspiration (EUS-FNA) ([ Fig. 1 ]). Fig. 1 Pretreatment imaging showing: a on a computed tomography (CT) scan, an 18-mm round lesion with arterial enhancement, characteristic of a pancreatic neuroendocrine tumor; b the lesion on magnetic resonance imaging (MRI); c a hypoechoic circular lesion on endoscopic ultrasound (EUS). The patient was prescribed diazoxide 50 mg, but this had to be discontinued because of acute fluid retention. She remained symptomatic but was a poor surgical candidate so was commenced on a low glycemic-index diet and octreotide. This was unsuccessful, so she remained on a continuous infusion of 10 % dextrose. The patient was therefore referred for EUS-guided radiofrequency ablation (RFA). RFA causes thermal coagulative necrosis through the administration of a high frequency current. The technique is now part of standard therapy for several tumors including hepatocellular carcinoma [ 1 ]. Recently a new monopolar RFA probe has been developed that can be placed down the working channel of a linear echoendoscope (Habib EUS-RFA catheter; Emcision Ltd, London, UK), enabling RFA to be administered under EUS guidance. To date it has been used in the management of two neuroendocrine tumors worldwide and in both cases the tumor decreased in size [ 2 ]. EUS-guided RFA was undertaken as a series of three treatments, each 1 week apart ([ Table 1 ], [ Video 1 ]). The procedures were performed with the patient under deep propofol sedation or general anesthesia. During the first procedure, three applications of RFA were administered at 10 W and were directed into the central part of the tumor ([ Fig. 2 ]). After the procedure, the patient’s glucose requirements initially decreased but increased back to pretreatment levels within 24 hours. A post-treatment CT scan on day 1 showed no complications and some central necrosis within the tumor ([ Fig. 3 ]).