RAD21 and CD4+/CD56+ hematodermic neoplasm: In addition, we identified a few mutations that have not been reported previously in BPDCN, including ETNK1, HNRNPK, HRAS, KDM6A, RAD21, SF3A1, and SH2B3, or have only been described in single case reports, including NF1, NOTCH1, and SUZ12 [12,17,18].