Blastic Plasmacytoid Dendritic Cell Neoplasm; A Report of Three Cases

Abstract

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare hematodermic myeloid malignancy that is known to be derived from plasmacytoid dendritic cells which are characterized by expression of CD4, CD56, and more specific markers such as CD123. Here, the authors present three cases of BPDCN diagnosed in the past two years and address different available diagnostic modalities such as morphology, immunohistochemistry, flow cytometry, and cytogenetics. Overall, we believe that although BPDCN is a rare diagnosis, it should not be left unchecked. Currently, available immunophenotyping markers are of great help, but the main clue to figure out the problem of BPDCN is clinicopathologic suspicion.

Keywords: Dendritic cells; Iran; Leukemia.

Figure1

The figure shows ulcerated skin nodule on the chest wall of case 1. The other two patients also had similar skin lesions.

Figure2

Multiple blasts (arrows) admixed with erythroid precursor cells (arrow heads) (bone marrow imprint, Wright-Giemsa stain, ×1000). Insert shows a blast in the concurrent peripheral blood (Wright-Giemsa stain, original magnification: ×1000). The blasts are medium-sized cells with irregular nuclei and scant cytoplasms which cannot be morphologically recognized as neoplastic dendritic cells. These images are related to case 1.

Figure3

Blast cells are separated from the epidermis by a well-defined Grenz zone (double-arrow) (upper left, H&E, ×200)(A); Monomorphic medium-sized blast cells with irregular nuclei (upper right, H&E, ×400)(B); Positive membranous CD56 immunostaining (lower left, ×200)(C); Positive cytoplasmic CD123 immunostaining (lower right, ×200)(D). Since CD123 is a specific marker for plasmacytoid dendritic cells, this positive result is a key finding without which an accurate diagnosis cannot be made. These images are related to case 2.

Figure4

Flow cytometry characteristics of BPDCN in a patient with about 90% blasts in bone marrow. The blasts are positive for CD45, CD4, CD56, HLA-DR, and negative for CD3, B-markers (CD19 and CD10), CD13, and CD14. Selecting a pertinent panel needs high suspicion for this neoplasm. These images are related to case 2.