We report a new case of blastic plasmacytoid dendritic cell
neoplasm (BPDCN) with extensive immunophenoptyping, genotyping (karyotype, array-comparative genomic hybridization, and fluorescent in situ hybridization), and long-term
tumor cells culture. BPDCN is a very rare and aggressive disease clinically characterized by a skin revealing localization more or less rapidly disseminating to the bone marrow and other organs with or without and
leukemia. The disease was initially phenotypically characterized by the expression of both CD4 and
CD56 antigens, whereas lymphoid and myeloid lineage
antigens were negative. A phenotypic link with
alpha-interferon (IFN-I)-producing plasmacytoid dendritic cells was demonstrated. The data collected in this case report provide additional
biological and genotypical data on
tumor cells of BPDCN. This study confirms the capability of
tumor cells to secrete IFN-I, demonstrated by
biological IFN-I activity of cultured cells and immunohistochemical expression of Mx-1
protein. Although a common genetic profile involving chromosomes 5, 6, 9, 12, 13, and 15 has been identified, no specific
genetic marker has been demonstrated that is specific to BPDCN. The demonstration of ETV6 gene deletion in this case deserves further investigations as a putative BPDCN marker.