The focal form of persistent hyperinsulinemic hypoglycemia of infancy.

Persistent hyperinsulinemic hypoglycemia of infancy (PHHI) is a disorder characterized by unregulated insulin release, leading to profound hypoglycemia with a major risk of brain damage if not recognized early. The occurrence of PHHI is low in the Western world (~1/50,000 live births), but it can be as high as 1/2,500 live births in communities with high consanguinity. PHHI may be differentiated from the other causes of neonatal hypoglycemia by demonstrating the persistence of an inappropriate serum insulin level, irrespective of blood glucose concentration, associated with a hypoketosis and a spectacular response to glucagon (1). In most cases and particularly those with severe hyperinsulinemic hypoglycemia of neonatal onset, medical therapy is not effective and, thus, surgery is mandatory to prevent permanent brain damage. Histological analyses of the resected pancreatic specimens have revealed that the disease does not correspond to a single pathological entity (2,3). Indeed, two different forms, which require radically different treatments, are recognized: a diffuse and a focal form. In the diffuse form of the disease, although the pancreas looks normal both macroand microscopically, a large or even near-total pancreatectomy is often not sufficient to cure the patient. On the contrary, in the focal form characterized by the presence of a small pancreatic “tumor,” the patient may be cured by a partial resection often restricted to the lesion. Clinically, the two forms are similar. The differential diagnosis can be made only by selective venous catheterization and insulin dosages associated with examination of intraoperative frozen sections (4–5). The focal form, which represents one-third of all cases in our series, is the subject of this study.