Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a hostile cutaneous malignancy with dismal prognosis and unknown etiology with rarity. Most patients received traditional chemotherapy only has one year of median survival time. This article reports an 81-year-old male patient with BPDCN who presented with skin manifestations and was diagnosed with positive CD4, CD56, and CD123 immunohistochemical results. Systematic examination revealed lung involvement and cytopenia.