CTNNB1 and neuroendocrine neoplasm: Notably, in the reported cases, the mutations involved the same exon of CTNNB1. Mutations affecting the same gene and the nuclear β-catenin staining pattern may be detected in other types of pancreatic neoplasms, but are more rarely observed, being present in < 10% of acinar cell carcinomas and in < 1% of neuroendocrine tumors [1, 38–40].