Alexis LeVee, MD1, Michael Kozak, DO2, Nathan Punwani, MD3, Jean Lopategui, MD2,
Sumire Kitahara, MD2, Noah Merin, MD4
Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare and aggressive hematologic malignancy characterized by
frequent cutaneous manifestations and diagnosed via immunophenotyping. BPDCN typically expresses CD56, CD4, and/
or CD123 expression by flow cytometry and immunohistochemistry and is confirmed by the expression of plasmacytoid
dendritic cell markers, including TCL1, CD303, CD304, and/or TCF4, in the absence of other lineage-specific markers.
We report a rare case of BPDCN that presented without cutaneous lesions and with a diagnostically challenging
immunophenotype consisting of dim CD4, lack of CD303, and expression of CD117. The patient also had an FMS-like
tyrosine kinase (FLT3) missense mutation at a variant allele frequency (VAF) of 20% and a TP53 frameshift mutation at a
VAF of 64%. Given the unusual presentation of BPDCN, high clinical suspicion was necessary for the diagnosis and clinical
awareness of this presentation is critical to avoid diagnostic delays.
