Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare and aggressive hematological neoplasm characterized by CD123+ (IL‐3 receptor) expression and at least one plasmacytoid dendritic cell marker in addition to expression of CD4+ and CD56+. This evidence concerns the gene CD4 and CD4+/CD56+ hematodermic neoplasm.