Heterotopic pancreas, periampullary somatostatinoma and type I neurofibromatosis: a pathogenetic proposal.

This case documents the association of ectopic pancreatic tissue with a duodenal somatostatinoma in a patient with type I neurofibromatosis. Pancreatic ducts have been noted within the centres of somatostatinomas, but little significance has been attached to this finding. Here we describe a patient in whom a separate proliferation of somatostatin cells occurred in association with the ectopic pancreatic ductular epithelium. This lesion bore a striking resemblance to the ductulo-insular or ductulo-endocrine complexes that are seen in nesidioblastosis in the pancreas. We therefore postulate that the ducts, which are sequestered within somatostatinomas, are of pathogenetic significance. The somatostatin-producing cells arise from these ducts, very much in the fashion of ductulo-endocrine complexes in nesidioblastosis.