Unusual presentation of blastic plasmacytoid dendritic cell neoplasm: Pitfalls in other hematolymphoid neoplasms

Abstract Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare CD4+/CD56+ hematological malignancy with aggressive clinical course and poor prognosis. Histologically, BPDCN is characterized by a diffuse, monomorphous infiltration of cutaneous, subcutaneous, and sometimes other tissues such as lymph nodes and bone marrow, by medium-sized neoplastic cells with blastoid morphology. Typically, there is absence of lymphocytic infiltrate. Diagnosis relies on immunophenotypic expression of CD4, CD56, and the more specific markers of plasmacytoid dendritic cells CD123, CD303/BDCA2, and TCL1. We report a case of a 57-year-old man who presented a 4 cm-long solitary, erythemateous lesion on t…