Since KRAS mutation occurred in endometrial cancer was related to the mucinous metaplasia [12, 14–16], and Liu et al. also found that the incidence of KRAS mutation was higher in the PPE lesions with mucinous metaplasia; it was possible that the presence of KRAS mutation in PPE was determined by the mucinous differentiation [11] rather than the classification of PPE. Here, KRAS is linked to endometrial cancer.