Adult onset nesidioblastosis after gastric bypass surgery, a clinical and pathologic review

Despite the many benefits of bariatric surgery in patients with morbid obesity, concerns have been raised over its association with severe hyperinsulinemic hypoglycemia and nesidioblastosis following Roux-en-Y gastric bypass surgery. Cases have been described with severe post-prandial hypoglycemia with neurological symptoms following surgery. Some of these cases are recalcitrant to medical treatment and may require partial pancreatectomy. Histological examination of the resected pancreas specimens shows features of adult nesidioblastosis characterized by hyperplasia of islets of Langerhans and beta cell hyperplasia and hypertrophy. Although the underlying mechanisms of gastric bypass-associated nesidioblastosis and hypoglycemia are still not fully understood, the exaggerated gut hormone response to altered nutrient flow in Roux-en-Y gastric bypass may be the cause of nesidioblastosis, hyperinsulinemia, hypoglycemia, and relevant neurological symptoms. We summarize the clinical and pathological features of adult nesidioblastosis following the Roux-en-Y gastric bypass procedure. The underlying mechanisms of post gastric bypass-associated hypoglycemia and nesidioblastosis are also discussed in this review.