Nesidioblastosis post-bariatric surgery in an adult patient: a case report and review of literature.

Introduction and importance: Adult-onset nesidioblastosis is an exceedingly rare yet significant cause of persistent hyperinsulinemic hypoglycemia. This condition is often associated to bariatric surgeries such as Roux-en-Y gastric bypass and sleeve gastrectomy. Characterized by abnormal β-cell hyperplasia and hypertrophy, its diagnosis presents a unique challenge due to overlapping features with insulinomas and post-bariatric hypoglycemia syndrome (PBHS). Case presentation: We report a 55-year-old woman with a history of gastric sleeve and Roux-en-Y gastric bypass surgeries who presented with a 1.5-year history of recurrent hypoglycemic episodes. Her symptoms, including blurred vision, tremors, and altered consciousness, persisted despite medical therapy with octreotide, acarbose, and nifedipine. Extensive imaging, including magnetic resonance imaging and endoscopic ultrasound, ruled out insulinomas, raising suspicion of non-insulinoma pancreatogenous hypoglycemia syndrome. The patient underwent laparoscopic subtotal distal pancreatectomy with spleen preservation. Histopathological examination confirmed nesidioblastosis, revealing irregular islet distribution and β-cell hypertrophy. Post-surgery, the patient achieved normoglycemia without recurrence of hypoglycemic episodes during follow-up. Discussion: This case highlights the complexity of diagnosing nesidioblastosis in adults, especially following bariatric surgeries. Nesidioblastosis involves β-cell hyperplasia and hypertrophy driven by hormonal factors like GLP-1, whereas PBHS results from altered incretin patterns causing excessive insulin release. Advanced imaging and multidisciplinary collaboration are important for accurate diagnosis. Surgical management remains a cornerstone for refractory cases, as demonstrated in this patient's remarkable recovery. Conclusion: Nesidioblastosis is a rare condition but should be considered in the differential diagnosis of post-bariatric surgery hypoglycemia. This case highlights the importance of distinguishing nesidioblastosis from PBHS to ensure appropriate and effective management strategies.