Blastic plasmacytoid dendritic cell neoplasm or CD4+ CD56+ acute myeloid leukemia: A case report.

Blastic plasmacytoid dendritic-cell neoplasm (BPDCN) is an extremely rare disease that originates from dendritic cells, characterized by co-expression of CD4 and CD56 without any other lineage-specific markers. It is associated with a poor prognosis. Previously, it was referred to by several names, including blastic NK-cell lymphoma, agranular CD4+ natural killer cell leukemia, and agranular CD4+CD56+ hematodermic neoplasm. The various nomenclatures and its evolution reflect the uncertainty of its histogenesis and the challenges involved in describing this hematopoietic neoplasm. Diagnosis challenge is due to similarities with CD4+CD56+ acute myeloid leukemia (AML) and histiocytic sarcoma (HS) immunophenotypic and histopathological features. We report a case of a 42-year-old male who presented with skin lesions and pancytopenia. While biologists suspected the diagnosis of BPDCN or CD4+ CD56+ AML based on the flow cytometry (FCM), anatomic pathologists retained the diagnosis of HS. The patient didn't respond to a systemic combination chemotherapy regimen and passed away rapidly. BPDCN diagnosis requires careful and exhaustive analyses in order to formulate the most appropriate therapeutic plan and to improve its prognosis.