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Case Study: The Pathology of Nesidioblastosis

An African-American male was diagnosed with heart failure at age 38 due to severe hypertension. At age 40, patient weighed 166lbs and he had normal glucose tolerance test. Three years later, patient weighed 275 lbs due to unknown reason and he was diagnosed with type I diabetes based on a random blood glucose of 684mg/dl accompanied by ketonemia and a metabolic acidosis. Patient was discharged from hospital on twice daily NPH and regular insulin. Over the next four years, patient was re-admitted to hospital several times due to chest pain, heart failure, UTI. During these crises, patient blood glucose remained above 300mg/dl despite large dose of insulin and only dropped when the precipitate causes resolved. Meanwhile, the patient continued to gain weight.

At age 49, he was hospitalized for urethral stricture. During his hospital stay, his serum glucose dropped to <50mg/dl while on his usual dose of insulin and low-calorie diet. His insulin therapy was discontinued and his serum glucose level on diet alone were between 90-120mg/dl. He was not started on oral diabetes meds and was discharged on only a low-calorie diet. Following his discharge, patient’s glucose reading remained normal without insulin or oral med. Pt didn’t not adhere to his low-calorie diet and continued to gain weight. His wife noticed that he became confused between 3AM-5AM and gave him orange juice, after which his confusion resolved. Eventually, his confusion became so severe that he had to be hospitalized; blood glucose reading was 22mg/dl. Upon admission to hospital, the patient blood glucose dropped to 28mg/dl 5 hours after glucose infusion and his serum insulin was high at 264 pmol/L, which indicated that patient had hyperinsulinemic hypoglycemia.

After multiple tests had ruled out all possible causes, an excised pancreas showed an increase in the total number of islets, which were enlarged, varied in size and shape, and showed nuclear polymorphism. Adjacent to the pancreatic ducts islet, cell neoformation was noted and atypically shaped islets were seen in the peripancreatic fat and pancreatic fibrous septa. All of these features are characteristic of nesidioblastosis. Nesidoblastosis is a form of acquired hyperinsulinism associated with B-cell hyperplasia. Few of these cases had been described in patients with diabetes. Insulinoma rarely occurs in either type 1 or type 2 patients.

After the surgery, the patient’s diabetes was well controlled without any meds or insulin. The patient believed that surgery had cured his diabetes. He was lost to follow up after his subtotal pancreatectomy.