Endocrine Abstracts

Background: Insulinoma is a rare pancreatic neuroendocrine tumor but a life-threatening condition if untreated. Surgical resection is the standard of care with a high cure rate for benign insulinomas but complications can occur in nearly 30% of cases. New non-surgical mini-invasive ablative therapies can be considered in patients with benign insulinoma who are either unfit for surgery or refuse it, although current data are scarce and long-term outcomes are unknown.

Aim: We describe the case of a benign and small insulinoma successfully treated with endoscopic ultrasound (EUS) guided radiofrequency ablation (RFA).

Case description: A non-diabetic 69 year old woman presented with a 5 months history of recurrent episodes of sweating, tremor and refractory focal seizures despite levetiracetam therapy. During one of these episodes, a low capillary glucose level of 2.9 mmol/l was found with rapid normalization following glucose infusion. The patient was admitted to our hospital for a fasting test which confirmed the diagnosis of insulinoma based on the following laboratory findings: symptomatic low plasma glucose level of 2.5 mmol/l (normal range 3–5.6) within 28 hours of fasting, high plasma insulin and C-Peptide levels of 13.8 mU/l (3–13) and 2.6 ug/l (1.0–3.1) respectively. Screening for both sulphonylurea hyoglycaemic agents and circulating insulin antibodies was negative. Abdominal MRI and ⁶⁸Ga-DOTATATE PET CT were inconclusive. The EUS guided fine needle aspiration confirmed a 12 mm well differentiated G2 (Ki 67 < 2%) neuroendocrine tumor located on the pancreas body. Symptoms of hypoglycemia were controlled with diet therapy. A multidisciplinary committee with the hepatobiliary surgery unit agreed to assess a minimally invasive endoscopic technique as an alternative to surgery. EUS-guided RFA of the pancreatic tumor was carried out using EUSRA^TM needle (19G, Teawoong). Apart from a mild transient fever that occurred 3 days after the procedure and treated with antibiotics, outcomes were favorable. The patient achieved symptomatic relief and biochemical normalization, and remained euglycemic during a follow-up of 2 months as confirmed by continuous glucose monitoring system.

Conclusion: This report adds to the emerging evidence of benign insulinoma being successfully treated by EUS-RFA, which may represent a potential alternative to surgery in selected cases. Further studies including larger patient samples are warranted to establish the safety and long-term efficacy of EUS-RFA in this setting.