BPDCN

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) CD45: CD45 expression may range from dim to moderate Expression expected: CD4, CD56 (bright), CD36, CD38, CD43, CD45, CD71, HLA-DR, Plasmacytoid dendritic cell (PDC) associated markers: CD123, CD303, CD304, TCF4, TCL1 .

CD7 and CD33 are relatively commonly expressed. TdT is positive in approximately one-third of the cases, occasional cases may express CD117. B

WHO diagnostic criteria allow BPDCN to be diagnosed:

• in the presence of CD123 and one other PDC-associated marker in addition to CD4 and/or CD56,
• in the presence of three PDC-associated markers and the absence of CD34 and other cell type-specific markers including CD3, CD14, CD19, lysozyme, and MPO.

Given the presence of other hematologic malignancies with similar phenotypes, correlation with histomorphology, clinical information and IHC studies is always necessary to make a definitive diagnosis of BPDCN.