CD4 and neoplasm: Initially named blastic NK/T cell lymphoma or agranular CD4+/CD56+ hematodermic neoplasm/tumour [6, 9, 10, 11], BPDCN is –according to the current WHO classification- classified as an acute myeloid leukemia-related precursor neoplasm [12] that has been shown to derive from precursors of plasmacytoid dendritic cells [13, 14,15, 16].