BACKGROUND Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare and aggressive hematologic malignancy. This disease almost always presents with cutaneous involvement. METHODS The 1st patient was a 16-year-old girl who presented with recurrent epistaxis. The 2nd patient was a 17-year-old female who presented with nasal obstruction and voice change for a month. METHODS In the 1st patient, sinonasal computed tomography (CT) revealed a 2.9-cm sized, polypoid mass in the nasal cavity. In the 2nd patient, CT scans revealed a large enhancing nasopharyngeal mass involving adenoid and several small indeterminate lymph nodes at the neck. Cutaneous examination was unremarkable for either patient. Biopsy of these 2 masses and bone marrow biopsy were performed. Histologic diagnosis of the 2 cases was BPDCN. METHODS Both patients were treated with induction chemotherapy and received allogenic peripheral blood stem-cell transplant. RESULTS No relapse was observed in the 2 patients for 14 and 11 months, respectively, after transplantation. Interestingly, they had no skin lesions at initial diagnosis or during the course of their illness. CONCLUSIONS We 1st identified nasal cavity as an unusual site of BPDCN. BPDCN should be considered in differential diagnosis of blastic leukemia with an undifferentiated and ambiguous immunophenotype despite the absence of skin lesions.