Endoscopic ultrasound-guided ethanol ablation for functioning insulinoma

BACKGROUND: Most diagnosed pancreatic neuroendocrine tumors (pNETs) are nonfunctioning tumors (90.8%); the remaining 9% are malignant functioning tumors. While surgical resection is the standard of care, alternative management options may be mandated in symptomatic patients who refuse or are ineligible for surgery. We present a case of endoscopic ultrasound (EUS)-guided ethanol ablation of symptomatic insulinoma in a patient who refused surgery. CASE PRESENTATION: A 35-year-old man was referred to our facility with suspected insulinoma for EUS evaluation. During a 48-h supervised fast, a plasma glucose of 30 mg/dl was obtained with a corresponding serum insulin level of 235 μIU/mL (normal: 20–80) and C-peptide level of 19.9 ng/mL (normal: 2.8–9.9). Computed tomography abdomen revealed a normal pancreas with no detected masses. On admission, he was on intravenous glucose 25% at an infusion rate of 250 mL/h and octreotide (150 mcg subcutaneously three times daily). EUS examination revealed a small hypoechoic pancreatic tail mass 2 cm ×1.5 cm with no vascular involvement or detected lymph nodes. EUS-fine needle aspiration was done using a 25G needle. Pathological examination was consistent with NET. The patient's family initially refused surgery; EUS-guided ethanol ablation was therefore considered. The lesion was injected with 3 mL of ethanol using 25G needle resulting in a hyperechoic blush within the center of the tumor. Following the procedure, there was partial clinical success with the patient's glucose infusion rate decreased to 100 mL/h. After 3 days, a second session was considered. The lesion was re-injected with 3 mL of ethanol using 22G needle resulting in a hyperechoic blush of the lesion. Again, there was partial clinical success with the patient's glucose infusion rate decreased to 50 mL/h. There were no postprocedural complications. The patient's family decided to do surgery and distal pancreatectomy was done. DISCUSSION: EUS-guided ethanol ablation of functioning pNETs is a less common therapeutic tool. A recent literature review showed 19 patients who underwent EUS-guided ethanol ablation of functioning pNETs from 2006 to 2015 with technical and clinical success in 100% of cases. This case reports another EUS-guided ethanol ablation of functioning insulinoma added to the documented cases, with partial clinical success. Despite partial clinical success, EUS-guided ethanol ablation is feasible and safe when applied to symptom relief in functioning tumors in patients who refuse or are ineligible for surgery.