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+. The gene discussed is NCAM1; the disease is hematopoietic and lymphoid system neoplasm.