Blastic Plasmacytoid Dendritic Cell Neoplasm: Report of a Case with Atypical Cytology and Immunophenotype

Blastic Plasmacytoid Dendritic Cell Neoplasm (BPDCN) or Plasmacytoid Dendritic Cell Leukemia (pDCL) is a rare and aggressive malignancy, whose diagnosis is mainly based on phenotypic characterization of the blastic cells with CD4+/CD56+ antigens. We report a BPDCN case with a blastic population expressing CD4 with no CD56 expression. In cytology, the classical “pearl necklace” aspect was missing. The diagnosis was made thanks to the specific BPDCN markers, namely CD303 (BDCA2), CD304 (BDCA4), and cTCL1. Biologists should be aware of this atypical presentation.