Clinical Features and Outcomes of 24 Cases of Blastic Plasmacytoid Dendritic Cell Neoplasm-Single Institutional Experience

Background: Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare, aggressive hematopoietic malignancy originating from precursor plasmacytoid dendritic cells. Clinically, patients usually present with skin lesions and simultaneous involvement of peripheral blood, bone marrow, lymph node, spleen and central nervous system. Median survival from diagnosis has been reported to range from 9 to 12 months (Julia F et al. Br J Dermatol. 2013;579-86). The optimal treatment for BPDCN has not been established yet. Majority of patients demonstrate response to lymphoma or acute lymphoblastic leukemia-like chemotherapy induction regimens.  A consolidation with autologous or allogeneic hematopoietic stem cell transplantation may improve outcome of selected patients. Limited data are available regarding prognostic and predictive factors.   In this study we analyzed clinical and laboratory characteristics and assessed their impact on clinical outcome. 

Methods and Materials: Patients with diagnosis of BPDCN at Moffitt Cancer Center between 2000 and 2015 were retrieved from a clinical database.   The diagnosis was confirmed by morphology, laboratory data, and immunopehnotying, according to 2008 WHO Classification of Hematopoietic Neoplasms. The relevant clinicopathologic features extracted from electronic medical records were recorded. Treatment modalities and responses to therapy were correlated with clinical outcomes.  A univariate linear discriminant analysis was used for risk stratification. Overall survival was analyzed by Kaplan-Meier method.

Results: We identified 24 patients with a median age of 74 years (range: 36-94 years) and a male:female ratio of 23:1. Mean hemoglobin was 11.83  2.48 g/dL; mean platelet count was 134 ± 84 k/µL; and mean white blood count was 6.34 ± 7.25 k/µL. Only one patient had an Eastern Cooperative Oncology Group (ECOG) performance status greater than 2.   Four patients demonstrated skin lesions only. Twenty patients (83.3%) demonstrated extracutaneous or systemic involvements. Peripheral blood, bone marrow, lymph node, spleen and cerebrospinal fluid (CSF) involvements were found in 11 (45.8%), 16 (66.7%), 8(33.3%), and 4(17%) patients, respectively. Six of 20 (30%) patients with systemic involvement were treated with CHOP. Two of 6 patients were treated with hyper-CVAD followed by an allogeneic hematopoietic stem cell transplant. Autologous transplant was administered to one patient who was treated with both CHOP and ICE induction regimens.  Median overall survival (OS) of the cohort was 49.9 months (95%CI, 19.9 – 81 months) and median follow up duration was 33.5 months (95% CI, 3-147 months). Statistical analysis showed the following parameters were not prognostic predictors of OS at diagnosis:  hemoglobin level (<10 g/dL), leukocytosis (>11,000/ul), thrombocytopenia (<100,000/ul), age >60, peripheral blood and bone marrow involvement (p=0.51, p=0.278, p=0.684, p=0.9288, p=0.2074, and p=0.8633, respectively). Lymph node involvement at diagnosis was associated with a shorter OS compared to those without lymph node involvement (p=0.0305). CHOP versus more aggressive chemotherapies did not show difference in OS (p=0.8939). Bone marrow transplant (1 autologous and 2 allogeneic) showed a trend to have longer OS (86 versus 64 months; p=0.12).

Conclusion:  BPDCN has an aggressive biological behavior.  Median overall survival of 49.9 months observed in our study compares favorably with OS of 12 months in previous reports. Lymph node involvement at diagnosis may have adverse impact on clinical outcomes. Larger scale studies are needed to identify risk factors that may have impact on outcomes and to establish standardized therapy in patients with BPDCN.