Rare functioning pancreatic endocrine tumors.

a Department of Gastroenterology, Beaujon Hospital, Clichy , France; b Department of Oncology, Institut Català d’Oncologia, Barcelona , Spain; c Department of Surgery, Verona University, Verona , Italy; d Department of Endocrinology and Metabolism, Genimatas Hospital, Athens , Greece; e Department of Gastroenterology, Beaujon Hospital, Clichy , France; f Department of Endocrinology, Erasmus MC University, Rotterdam , The Netherlands; g Department of Internal Medicine, Martin University, Martin , Slovakia; h Department of Propaedeutic Internal Medicine, Laiko Hospital, Athens , Greece; i Department of Nuclear Medicine, Erasmus MC University, Rotterdam , The Netherlands; j Department of Gastroenterology, Beaujon Hospital, Clichy , France; k Department of Gastroenterology, Royal Free Hospital, London , UK; l Department of Cell Biology, National Institute of Health, Bethesda, Md. , USA; m Department of Endocrinology, University Hospital, Uppsala , Sweden