Cytomorphological and immunophenotypic characteristics of blastic plasmacytoid dendritic cell neoplasm involving central nervous system: a case report and review of literature.

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare, aggressive hematopoietic neoplasm derived from precursors of plasmacytoid dendritic cells. We describe cytomorphological and immunophenotypic features of BPDCN in cerebrospinal fluid (CSF) in a 66-year-old patient who presented with delayed central nervous system relapse. Morphological examination showed dense infiltration by monotonous population of intermediate-sized cells, resembling blasts. Nuclei had irregular contour with fine chromatin and prominent nucleoli. The cells had scant, pale blue, agranular cytoplasm. In some cells, intracytoplasmic vacuoles were also seen. No lymphoglandular bodies were seen. No mitosis or karyorrhexis were observed. On immunophenotyping, these cells were positive for CD45dim, CD123dim, HLA-DR, CD56, CD36bright, TCL1, CD4, CD117, CD38dim and negative for CD13, CD33, CD34, CD14, CD64 and CD16. The relevance of clinical suspicion, cytological recognition, and inclusion of BPDCN specific immunophenotypic markers is emphasized.