Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare, clinically aggressive hematologic malignancy that most commonly manifests as cutaneous lesions with or without bone marrow involvement and leukemic dissemination.
The nomenclature used to describe this entity has evolved over the years as understanding of the underlying biology has improved. The tumor was initially described in 1995 as an acute agranular CD4-positive natural killer (NK) cell leukemia . Based on the blastic appearance and CD56 expression, the term "blastic NK cell lymphoma" was used. Subsequently, the term "agranular CD4+CD56+ hematodermic neoplasm/tumor" was coined based on the immunophenotype and a predilection for skin involvement. However, following the discovery and confirmation that BPDCN is derived from plasmacytoid dendritic cells (type 2 dendritic cells), the current nomenclature, blastic plasmacytoid dendritic cell neoplasm, was chosen to describe the entity in the 2008 WHO classification of tumors of the hematopoietic and lymphoid tissues .
The epidemiology, clinical manifestations, pathologic features, diagnosis, and management of BPDCN will be presented here. Chronic NK cell lymphocytosis and NK cell large granular lymphocyte leukemia are described separately. (See "Natural killer (NK) cell large granular lymphocyte leukemia".)
Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare hematologic neoplasm and the exact incidence is unknown. The precise incidence of BPDCN is difficult to estimate due to constantly changing nomenclature and lack of precise defining criteria prior to the 2008 WHO classification system. BPDCN represent 0.7 percent of primary cutaneous skin lymphomas . However, cutaneous lymphoma registries likely underestimate the true incidence of BPDCN because a small but significant proportion of patients present without skin lesions .
BPDCN occurs in all races and all geographic locations; however, there are few data regarding whether the incidence varies by ethnicity or geography. BPDCN has been described in all age groups, but is most common in adults [3,5,6]; the majority of patients are older adults and the median age at diagnosis is 65 to 67 years. There is a modest male predominance with a male to female ratio of approximately 2.5:1.