Nesidioblastosis

Nesidioblastosis is beta cell hyperplasia, consisting of the proliferation of islet cells from pancreatic ducts. It is a cause of hypoglycemia and hyperinsulinemia in a number of infants and newborns. Recently, this condition has been recognized in adolescents and adults and occurs in 5% of patients with hyperinsulinism. Prolonged hypoglycemia leads to mental retardation in most of these children. Near-total (95%-98%) pancreatectomy appears to offer the best results.

The problem with the term ‘nesidioblastosis’ is that nesidioblastosis is a normal phase of fetal islet development rather than a pathologic entity.

Nesidioblastosis is a controversial medical term for hyperinsulinemic hypoglycemia attributed to excessive function of pancreatic beta cells with an abnormal microscopic appearance. The term was coined in the first half of the 20th century. The abnormal histologic aspects of the tissue included the presence of islet cell enlargement, islet cell dysplasia, beta cells budding from ductal epithelium, and islets in apposition to ducts.

By the 1970s, nesidioblastosis was primarily used to describe the pancreatic dysfunction associated with persistent congenital hyperinsulinism and in most cases from the 1970s until the 1980s, it was used as a synonym for what is now referred to as congenital hyperinsulinism. Most congenital hyperinsulinism is caused by different mechanisms than excessive proliferation of beta cells in a fetal pattern and the term fell into disfavor after it was recognized in the late 1980s that the characteristic tissue features were sometimes seen in pancreatic tissue from normal infants and even adults, and is not consistently associated with hyperinsulinemic hypoglycemia.

However, the term has been resurrected in recent years to describe a form of acquired hyperinsulinism with beta cell hyperplasia found in adults, especially after gastrointestinal surgery.