CD4 and neoplasm: It may also express other antigens negative in normal pDCs, including interferon regulatory factor 4 (IRF4), BCL6, and BCL2 (the latter provides a therapeutic target in the affected individuals) [3,13,14]. In this case, the patient's tumor cells were positive for CD123, CD4, HLA-DR, and cTCL1, which is consistent with the diagnosis of BPDCN based on the typical immunophenotype.