Adult nesidioblastosis. Clinicopathologic correlation between pre-operative selective arterial calcium stimulation studies and post-operative pathologic findings.

CONTEXT: Adult nesidioblastosis, a rare form of abnormal islet cell proliferation arising from the pancreatic ductal epithelium, is usually associated with severe hyperinsulinemic hypoglycemia. Overall, seventy-three cases of nesidioblastosis have been described in the English literature since the entity was first described by Laidlaw in 1938, and only a minute fraction of these have occurred in children. CASE REPORT: We present the case of a previously healthy 45-year-old woman with new-onset severe hypoglycemia 4 and seizures. The differential diagnosis at presentation included factitious hypoglycemia and insulinoma. Extensive imaging and laboratory examination, including repeated CT and MRI scans, toxicology assays, and insulin-based chemical studies, were either inconclusive or negative. Subsequent testing involved stimulation of the pancreas through cannulation of the pancreatic vascular supply by interventional radiology. This testing revealed marked insulin release to low-level calcium challenge across multiple pancreatic segments. Based on these functional radiological findings, the patient underwent subtotal pancreatectomy. Gross and histologic examination of the resected tissue revealed no evidence of a pancreatic mass. Diffuse islet cell hyperplasia was noted in a pattern consistent with nesidioblastosis. The patient remained normoglycemic in the months following partial pancreatectomy.
CONCLUSIONS: Nesidioblastosis, while exceedingly rare in adult populations, should be considered in the differential diagnosis of severe hypoglycemia. This diagnosis cannot be easily made through routine diagnostic laboratory or radiological procedures and likely requires a histological tissue diagnosis.