IntroductionBlastic plasmacytoid dendritic cell neoplasm (BPDCN) is an uncommon hematologic malignancy originating from plasmacytoid dendritic cells (1). These cells harbor a specific immunophenotype, positive for CD4 and CD56 and negative for CD3 and CD19(2). The BPDCN is classified as a separate category besides acute myeloid leukemia and B/T cell leukemia/lymphoma in the 2022 World Health Organization Classification of Hematolymphoid Tumors 5th edition (1). It commonly involves skin, and skin lesions including nodules and papules can be the only disease presentation; however, it can involve bone marrow, lymph nodes and spleen (3, 4). Leukemic reaction may also occur. Breast tissue infiltration by BPDCN has been reported in one case (4). Aggressive course and poor prognosis of the patient as well as diagnosis difficulties for pathologists and clinicians are problems that have not been resolved so far. Here we describe a case of BPDCN, someone who presented with a forehead skin lesion with focus on histopathologic diagnosis. Immunophenotyping by immunohistochemistry methods confirmed the diagnosis.