Blastic plasmacytoid dendritic cell neoplasm

Blastic plasmacytoid dendritic cell neoplasm
CD4+ CD56+ lymphoma

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare hematologic malignancy. It was initially regarded as a form of lymphocyte-derived cutaneous lymphoma and alternatively named CD4+CD56+ hematodermic tumor, blastic NK cell lymphoma,^[1] and agranular CD4+ NK cell leukemia.^[2] Later, however, the disease was determined to be a malignancy of plasmacytoid dendritic cells rather than lymphocytes and therefore termed blastic plasmacytoid dendritic cell neoplasm. In 2016, the World Health Organization designated BPDCN to be in its own separate category within the myeloid class of neoplasms.^[3] It is estimated that BPDCN constitutes 0.44% of all hematological malignancies.^[4]

Blastic plasmacytoid dendritic cell neoplasm is an aggressive malignancy with features of cutaneous lymphoma (e.g. malignant plasmacytoid dendritic cell infiltrations into the skin to form single or multiple lesions) and/or leukemia (i.e. malignant plasmacytoid dendritic cells in blood and bone marrow).^[2] While commonly presenting with these clinical features, BPDCN, particularly in its more advanced stages, may also involve malignant plasmacytoid dendritic cell infiltrations in and thereby injury to the liver, spleen, lymph nodes, central nervous system, or other tissues. The neoplasm occurs in individuals of all ages but predominates in the elderly; in children, it afflicts males and females equally but in adults is far more common (~75% of cases) in males.^[5]

Blastic plasmacytoid dendritic cell neoplasm typically responds to chemotherapy regimens used to treat hematological malignancies. All too often, however, the disease rapidly recurs and does so in a more drug-resistant form.^[5] Furthermore, the disease may occur in association with the myelodysplastic syndrome or transform to acute myeloid leukemia.^[4] Consequently, BPDCN has a very low 5 year survival rate.^[5] Current translational research studies on treating BPDCN have therefore focused on non-chemotherapeutic regimens that target the molecular pathways which may promote the disease.^[6]