Blastic plasmacytoid dendritic cell neoplasm (BPDCN, blastic NK-cell lymphoma, agranular CD4+ NK-cell leukemia, blastic NK leukemia/lymphoma, agranular CD4+ CD56+ hematodermic neoplasm) is a rare, highly aggressive tumor that is caused by white blood cells (lymphoma). Reddish-brown nodules or bruise-like lesions on the skin are usually the only sign of the disease. This kind of tumor is treated with chemotherapy and stem cell therapy. The prognosis of patients with BPDCN is poor with a median survival of 12-14 months, although recent successes in stem cell therapy give rise to hope.
In most of the cases, cutaneous lesions or reddish-brown nodules on the skin are usually the only sign of the disease.
This type of cancer is caused by white blood cells called dendritic cells.
From its discovery in 1994 until 2008, the exact cause of the disease was unknown. During this time, different white blood cell types were suggested to cause BPDCN, hence it was frequently renamed (agranular CD4+ natural killer cell leukemia, blastic natural killer leukemia/lymphoma, agranular CD4+CD56+ hematodermic neoplasm). In 2008 the World Health Organization introduced the name “blastic plasmacytoid dendritic cell neoplasm”.
To diagnose BPDCN, a small sample of the tumor tissue is taken from the patient (biopsy). The white blood cells in this tissue are then analyzed to determine, which proteins they express on their surface. This allows for the exact identification of white blood cells causing the disease, which are mutated dendritic cells in the case of BPDCN.
The diagnosis relies on the immunophenotypic features of the malignant cells. Flow cytometry is preferred over immunohistochemical analysis since it allows for the examination of more markers and their intensity determination. Diagnosis rests upon the demonstration of the surface proteins CD4 and CD56, together with markers more restricted to dendritic cells (BDCA-2, CD123, TCL1, CD2AP, BCL11a) and negativity for lymphoid, NK and myeloid lineage-associated antigens.
BPDCN is a rapidly evolving disease. The disease follows a short course and leukemia is the common terminal stage. The prognosis of patients with BPDCN is poor, with a median survival of 12-14 months. Acute lymphoblastic leukemia-type treatment is advised and a promising initial response may occur, but most patients subsequently relapse within a year. Long-term cancer free states (remissions) have been rarely reported in younger patients who received acute leukemia-type induction therapy and allogeneic stem cell transplantation.
Due to its rarity and only recent recognition as a distinct disease, no standardized therapeutic approach has been established for BPDCN. In different studies, a high-dose chemotherapy/radiotherapy followed by allogeneic stem cell transplantation performed after the first complete cancer-free state (remission) offered the highest curative potential. While initial response to therapy may be accomplished with a variety of therapy regimens, sustained remission in adults has only been described in those who underwent allogeneic stem cell transplantation. These promising results indicate that allogeneic transplantation should be considered as front-line therapy for the treatment of this rare malignancy.