Plasmacytoid Dendritic Cell Proliferation Associated with Acute Myeloid Leukemia, Case Report and Review of Literature

We present a typical case of plasmacytoid dendritic cell proliferation associated with acute myeloid leukemia (pDC-AML). The patient was a 65-year-old male admitted for new onset progressive pancytopenia over the course of three weeks. Diagnostic marrow revealed 27% myeloblasts. In addition, flow cytometry and immunohistochemistry studies identified an 18% population of immature plasmacytoid dendritic cells. Baseline next-generation sequencing identified pathogenic mutations in ASXL1, EZH2, FLT3, and RUNX1. The patient underwent induction chemotherapy for a diagnosis of pDC-AML. One month after chemotherapy, evaluation for Measurable Residual Disease (MRD) using multiparameter flow cytometry was interpreted as negative with changes related to treatment. pDC-AML is a newly described rare subtype of acute myeloid leukemia which can impose diagnostic challenges. Clinical, pathologic, and molecular correlation are important to render an accurate final diagnosis. We review the published literature on pDC-AML cases and discuss pDC biology, and the process for differentiating the diagnosis of pDC-AML from those of blastic plasmacytoid dendritic cell neoplasm or mature plasmacytoid dendritic cell proliferations associated with other myeloid neoplasms. The AML MRD evaluation for pDC-AML is a particular challenge. To this end, additional molecular studies, including MRD tests using next-generation sequencing, can be of great help.