GNAS and serous cystadenoma: These mutations are important for distinguishing IPMNs from other pancreatic cystic lesions: while 91–99% of IPMNs have either KRAS and/or GNAS mutations without significant variation in degree of dysplasia [38,47], serous cystadenomas generally have neither mutation, and while not as sensitive, GNAS mutations can help distinguish IPMNs from mucinous cystic neoplasms, as will be discussed next [46].