Provisional Prognostic Score for Blastic Plasmacytoid Dendritic Cell Neoplasm

Background

BPDCN is an aggressive hematologic malignancy which often involves the skin. This disorder has gone through many iterations over the years, being classified initially as a blastic NK-cell lymphoma, then a subset of AML, and finally recognized as a unique myeloid neoplasm. While BPDCN often follows an aggressive course, its outcomes vary considerably. We conducted this study to develop a provisional BPDCN prognostic score (BPS) for this rare disease.

Methods

We used our constructed BPDCN database, which contains retrospective data on 273 cases. Such data included demographics such as sex, age, and race. It also included disease presentation symptoms, duration of symptoms before diagnosis, site(s) of the disease, blood counts, coexisting comorbidities, disease immunohistochemical and molecular phenotype, types of treatment, and survival outcomes. Of the 273 cases, only 218 had complete survival and outcomes data, the sample chosen for this study. Cox proportional-hazards model and Log-rank tests were used to assess the influence of clinicopathologic factors on overall survival (OS). We included factors that statistically impacted OS and scored them by the impact of their hazard ratios.

Results

The median OS of the cohort was 16 months. The following dichotomous variables were identified as impactful prognostic factors in this cohort: Age>60 (10 vs. 30 months), lymphadenopathy (14 vs. 42 months), bone marrow involvement (14 vs. NR months), splenomegaly (10 vs. 16 months), and disseminated skin disease (13 vs. NR months). A prognostic model was devised using these variables to identify different levels of risk. Each variable was assigned a score of 1 when present, except for age>60, splenomegaly, and disseminated skin disease, that were assigned 2 points each as they had the highest hazard ratios of all the other variables. In this exploratory cohort, low risk was assigned a score of 0-2, intermediate risk a score of 3-4, and high risk a score of 5-8. This prognostic score system led to our cohort's most optimal risk discriminatory model, where low, intermediate, and high risk had a median OS of NR, 24, and 10 months, respectively (p<0.0001).

Conclusion

This BPS is a promising new tool for risk-stratifying patients with BPDCN. However, it still requires prospective validation.