Background Blastic plasmacytoid dendritic cell neoplasm (BPDCN) represents the malignant counterpart derived from plasmacytoid dendritic cells. This rare entity is usually revealed and diagnosed on cutaneous lesions associated or not with a leukaemic component. The prognosis associated with BPDCN is very poor. Objectives To perform a retrospective review of BPDCN cases registered in the French Study Group on Cutaneous Lymphoma database from June 1995 to May 2008. Methods Forty-seven patients were included. Demographic data, initial staging, therapeutic management and outcome were recorded. Results The mean survival was 16.7 months (95% confidence interval 12.6-20.8). Only eight (17%) and one (2%) patients reached respectively 2 and 5 years of survival. Initial spreading of the disease did not represent, in this cohort, a reliable prognosis factor. The outcome was overall influenced by treatment provided. While radiation therapy, monochemotherapy or even polychemotherapy regimens did not significantly affect the course of the disease, the survival of bone marrow transplanted patients was significantly higher. Conclusions Despite the fact that BPDCN is often initially limited to the skin, only an aggressive initial therapy may improve the patients' prognosis. Local treatments, such radiation therapy, are definitively useless. Regardless of the initial extension of the disease, in our experience only bone marrow transplantation significantly improved the outcome.