Cytologically, NPM1-RARA-positive APL exhibited one different morphology from typical APL [44, 45], which was also found in the mouse model of NPM1-RARA [46], and clinically, it occasionally developed to aleukemic leukemia cutis with one relatively higher frequency compared to other variant APL [44, 47]. This evidence concerns the gene NPM1 and acute promyelocytic leukemia.