RB1 and neuroendocrine carcinoma: To help discriminate between these two groups of neoplasms, studies have found mutations in TP53 or Rb1 and abnormal p53 and Rb1 immunohistochemical staining, as well as KRAS and BRAF mutations, to be a feature of NEC; whereas immunohistochemical loss of DAXX/ATRX, mutations in MEN1 and immunohistochemical expression of CgA and SSTR-2a is more frequently found in pancreatic NET G3 [7, 8, 11–14].