MEN1 and pancreatic neuroendocrine tumor: Precursor lesions of GEP tumors that are suggestive of inherited conditions include gastric enterochromaffin-like cell (ECL) hyperplasia and gastrin-producing and/or somatostatin-producing cell hyperplasia that are associated to MEN1-related type II gastric and duodenal NETs, respectively, or islet hyperplasia, islet dysplasia and ductulo-insular complexes in the setting of MEN1- or VHL-related pancreatic NETs [54, 55].