Definition:

Pancreatic neuroendocrine tumors (PNETs), also known as islet cell tumors, are rare neoplasms that arise in the endocrine tissues of the pancreas. They may occur sporadically or in association with a genetic syndrome, such as multiple endocrine neoplasia type 1 (MEN1), Von Hippel-Landau (VHL) syndrome, neurofibromatosis type 1, or tuberous sclerosis. The most frequent genetic alterations in PNET occur in MEN1 (Multiple Endocrine Neoplasia-1 Gene), DAXX/ATRX (Death-Domain Associated Protein/Mental Retardation Syndrome X-Linked Genes) and the mTOR pathway (Mammalian Target of Rapamycin). A germline mutation in the MEN1 tumor suppressor gene causes MEN1, the above-mentioned autosomal dominant hereditary syndrome. Mutations of DAXX and ATRX are common and related to altered telomeres but not to prognosis.