nesidioblastosis

Nesidioblastosis is a medical condition characterized by diffuse or focal hyperplasia of pancreatic islet beta cells, leading to hyperinsulinemic hypoglycemia. The term originally described a congenital or neonatal form with widespread beta‑cell proliferation, but it is also used to describe postprandial hypoglycemia in adults after gastric bypass surgery, where diffuse islet cell hyperplasia may occur.

Pathophysiology and classification: In classic neonatal nesidioblastosis, beta cells proliferate and form budding islet cells (nesidioblasts) that originate from ductal epithelium, resulting in excessive insulin secretion. In adults, a similar pattern can occur after bariatric procedures, where altered gut hormones and incretin effects are thought to drive disproportionate insulin release. The condition can be diffuse, affecting the entire pancreas, or focal in rare cases.

Clinical features: Hypoglycemic episodes may present with sweating, tremor, palpitations, confusion, or seizures. In infants, symptoms typically appear in the first months of life; in adults, episodes are often postprandial and may be recurrent months to years after surgery. Symptoms improve with glucose intake and worsen during fasting or exercise.

Diagnosis: Diagnosis relies on documentation of hypoglycemia with inappropriately elevated insulin and C‑peptide during an episode, and exclusion of exogenous insulin or sulfonylurea use. Imaging is usually undertaken to exclude insulinoma; where uncertainty remains, selective arterial calcium stimulation testing with hepatic venous sampling can help localize disease. Histology from pancreatic tissue shows islet cell hyperplasia with nesidioblasts.

Treatment and prognosis: Acute management requires prompt correction of hypoglycemia. Medical therapy includes diazoxide to suppress insulin release and somatostatin analogues such as octreotide; dietary modification is important. Refractory diffuse disease may necessitate subtotal or near-total pancreatectomy, while focal lesions can sometimes be treated by limited resection. Prognosis varies; many patients respond to medical therapy, though some require surgical intervention and may develop persistent endocrine insufficiency.