Abstract
The patient was a 58-year-old man, who presented with a history of occasional episodes of loss of concentration before dinner since 2002. In 2003, fasting hypoglycemia was identified without suppression of insulin secretion. He was admitted subsequently to our hospital for further evaluation the hypoglycemia. The ratio of IRI to plasma glucose (PG) was 0.8-1.0. Abdominal CT showed no pancreatic tumor, and angiography of the splenic artery showed no definite tumor stain within the pancreas. However, based on the results of selective arterial calcium stimulation and hepatic venous sampling, the provisional diagnosis was a small insulinoma in the pancreatic body. The patient underwent subtotal distal pancreatectomy. However, histopathological and immunohistochemical examinations of the resected tissue showed hypertrophy the islets of Langerhans and β-cells around the pancreatic ducts. The final diagnosis was adult-onset nesidioblastosis. Postoperatively, the patient continued to exhibit hyperinsulinemia and nighttime hypoglycemia (30-40 mg/dl). Diazoxide treatment which was not approved in Japan for the management of nesidioblastoma, was started after obtaining informed consent, and demonstrated a noticeable effect immediately. To date, treatment with 200 mg/day diazoxide has resulted in amelioration the patient's nocturnal hypoglycemia and other symptoms. In conclusion, we experienced a rare case of adult-onset nesidioblastosis. Since preoperative diagnosis of adult-onset nesidioblastosis is difficult to confirm, there is no standardized management for this condition. The implemented treatment strategy in this patient suggests that diazoxide may be effective for nesidioblastosis in adults and could be useful for long-term treatment of patients with hypoglycemia and hyperinsulinemia after pancreatectomy.
