A 76-year-old man presented with an asymptomatic, solitary, 1.5 cm-sized, erythematous nodule on the upper trunk for a month. The lesion increased in size over time. The patient had been diagnosed with hypertension and trigeminal neuralgia. However, he had no history of any hematologic disease. Skin biopsy showed diffuse monomorphous infiltrates of small round cells separated by a grenz zone from the epidermis. In immunohistochemistry staining of CD4, CD56, CD123 showed positive results, while CD3 showed negative result. It was diagnosed as Blastic plasmacytoid dendritic cell neoplasm (BPDCN) and the patient was transferred to hematology. He took bone marrow biopsy and Positron Emission Tomography - Computed Tomography (PET-CT). Bone marrow biopsy and PET-CT was negative for distant metastasis and he took Intensity-modulated radiotherapy. BPDCN was defined in the 2008 World Health Organization Classification of Tumors of Hematopoietic and Lymphoid Tissue as a malignant proliferation of blastic plasmacytoid dendritic cells. Initially, it was described in 1990’s as agranular CD4+ natural killer cell leukemia due to its unique agranular morphology and phenotype (CD4+, CD56+, CD15+ and CD3-). BPDCN is highly malignant, with a mean survival time of 15.2 months. But, data are limited concerning patients with localized skin-limited BPDCN. Herein, we report a rare case of blastic plasmacytoid dendritic cell neoplasm.