Diagnosing BPDCN: What You Should Know About Key Markers and Tests

Why Diagnosing BPDCN is Difficult

Because blastic plasmacytoid dendritic cell neoplasm (BPDCN) is rare, diagnosis can be challenging. Many features of BPDCN overlap with those of other blood cancers, which often leads to misdiagnosis, delays in diagnosis, and ultimately impacts treatment outcomes. Determining whether an individual has BPDCN requires a comprehensive approach that includes physical exams, laboratory testing, and imaging.

Cell Markers Help Identify BPDCN

Since BPDCN is not common, it is important to recognize its specific features. One key way to identify BPDCN is through lab tests that evaluate markers on the surface of cells.

Doctors can determine whether a person has BPDCN by looking for a special combination of markers. BPDCN usually shows a pattern that includes three key markers: CD123, CD4, and CD56. In addition to those, the cells often have other markers like TCL1, TCF4, and CD303. This unique set of markers helps doctors distinguish BPDCN from other types of blood cancer and make a clear and accurate diagnosis.  

Understanding the markers for BPDCN has been helpful not only for diagnosis but also plays a role in treatment. For example, targeted therapies such as tagraxofusp (Elzonris), which binds to CD123, have been developed and specifically approved to treat BPDCN.

You can read more about BPDCN treatment options here.  

Skin biopsy: A Common Starting Point

One of the most common clinical presentations of BPDCN is skin lesions.  These occur in 90 percent of cases. These lesions can vary in size and color and can be found anywhere on the body.  Due to their appearance, they can be mistaken for rashes, bruises, or other skin conditions. 

A skin biopsy, commonly performed to evaluate these lesions, is the removal of a small sample of skin tissue to be examined under a microscope. This procedure is essential for confirming the diagnosis and guiding appropriate treatment.

Bone Marrow Biopsy Helps Determine Cancer State 

Bone marrow is a key site for diagnosis and blood cancer monitoring. A bone marrow biopsy involves the removal of a small sample of bone marrow.  This sample is then analyzed under a microscope to evaluate the presence of abnormal cells. 

The findings help determine how far the cancer has progressed and whether it has impacted blood cell production. Bone marrow evaluation is essential for staging BPDCN, planning treatment, and monitoring response to therapy.

Imaging Shows Where Else BPDCN May Be

Imaging studies play an important role in the evaluation and management of BPDCN. While skin and bone marrow are commonly involved, imaging helps assess whether the cancer has spread to internal organs, lymph nodes, or the central nervous system. Common imaging techniques include CT (computed tomography) scans and PET (positron emission tomography) scans, each providing detailed views of different parts of the body.

These scans are non-invasive and help clinicians to identify areas where cancer is present, determine the stage, and guide treatment decisions. Imaging may also be repeated over time to monitor how the cancer responds to therapy or to detect signs of relapse.

Central Nervous System Involvement Requires Careful Attention

BPDCN may impact the central nervous system (CNS), leading to neurological symptoms that differ in severity and how they appear.  Evaluation typically requires a lumbar puncture (spinal tap) to collect cerebrospinal fluid, which is then examined for cancerous cells.

Routine CNS evaluation is especially important in people with advanced BPDCN or who have relapsed. Early detection can support better symptom control and guide more tailored therapy plans.

To continue reading about BPDCN, take a look at our BPDCN 101 pages.

Because BPDCN is so rare, more real-world data is needed to improve diagnosis and outcomes. People with BPDCN can contribute by participating in simple surveys through HealthTree Cure Hub®. This helps researchers and clinicians understand more about the impact of BPDCN and develop better care strategies.

Join Cure Hub!

Sources: 

• BPDCN Standards of Care and Areas of Need
• Dana-Farber Approach to BPDCN Treatment
• BPDCN Histopathology