[Nesidioblastosis as extracolonic manifestation associated with adenomatous familial polyposis]

To describe the case of a patient with familial adenomatous polyposis (FAP) who developed organic hyperinsulinemia and hypoglycemia due to pancreatic nesidioblastosis.

FAP can be considered as one of the familial cancer syndromes. The development of endocrine tumors in these patients is an infrequent event, and most of these tumors have been well-differentiated thyroid neoplasms. To our knowledge, the occurrence of organic hyperinsulinemia in the context of FAP has not been reported.

Organic hyperinsulinemia was demonstrated during a 72-h fast, measuring insulin and C-peptide by RIA at the time of hypoglycemia. Immunohistochemistry for insulin and other pancreatic hormones was performed on the surgical pancreatic specimen.

The patient underwent a distal pancreatectomy with resolution of hypoglycemia. Histopathologically, the excised pancreas showed beta cell hyperplasia arising from the ductal epithelium. Such beta cells strongly immunostained for insulin, pancreatic polypeptide, and neuron-specific enolase.

The development of endocrine tumors in an inherited cancer syndromes such as FAP is rare. Such an association may suggest shared mechanisms of tumorigenesis. The case herein reported should prompt us to consider organic hyperinsulinism as an extracolonic manifestation of FAP.