EUS Identification and EUS-Guided Alcohol Ablation of Insulinoma in a Patient With Hypoglycemia and Roux-en-Y Gastric Bypass Surgery (RYGBS)

Introduction: Hypoglycemia is a known complication of bariatric surgery. The etiology of hypoglycemia after such surgeries can be challenging to diagnose. It is crucial to distinguish between reactive hypoglycemia and other possible causes of hyperinsulinemia. While EUS-guided alcohol ablation has been reported before in patients without RYGBS, to our knowledge, EUS identification and EUS-guided alcohol ablation in patients with gastric bypass has not been reported. Traditionally, EUS is not attempted in such a scenario since it can only examine the body and tail of the pancreas through a small gastric pouch. This case highlights the successful diagnosis and treatment of a patient with an insulinoma presenting 15 years after RYGBS with EUS-guided alcohol ablation. Case Description/Methods: 74-year-old male initially admitted for thigh abscess. Past medical history was significant for CAD, HTN, COPD, peptic ulcer disease, iron deficiency anemia, hypothyroidism, obesity, alcohol abuse, and RYGBS 15 years prior. Additionally, the patient had persistent postprandial hypoglycemia for years post-RYGBS. Laboratory results revealed blood glucose of 35 mg/dL. Fasting hypoglycemia continued despite inpatient diet modifications. Hypoglycemia laboratory evaluation included c-peptide 3.38 ng/mL, beta-hydroxybutyrate 0.09 mmol/L, insulin 11.0, proinsulin 11.6, insulin antibody < 0.4, and a positive glucagon challenge test. These findings were suggestive of insulinoma. CT abdomen and pelvis w/wo contrast identified no suspicious hepatic, pancreatic, adrenal, or splenic lesion. EUS discovered a 15x14 mm round mass in the body of the pancreas. EUS-guided FNA cytology with immunostains was consistent with a neuroendocrine tumor. Patient was deemed a non-surgical candidate due to major comorbidities and was thus offered alcohol ablation. EUS-guided alcohol ablation was performed with a total of 5 cc of absolute alcohol. Blood glucose level normalized the next day, and the patient was asymptomatic. His blood glucose level remained stable at 3 months follow up. Discussion: EUS localization of insulinomas can be challenging in patients with normal gastric anatomy and therefore is not widely used in patients post-RYGBS. EUS should be considered in patients with a history of bariatric surgery despite the fact that the anatomy lends itself to only partial examination of the pancreas as it may reveal an insulinoma.