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PubMed This is a summary of 20 peer-reviewed journal articles Updated
Oncology

Decoding Your Pathology and Flow Cytometry Reports

At a Glance

A BPDCN diagnosis is confirmed using flow cytometry to identify a specific combination of surface proteins, most importantly CD123, CD4, and CD56. Pathologists also use markers like TCF4 and TCL1, along with genetic testing, to distinguish BPDCN from other similar blood cancers.

When you look at your pathology report, it can seem like a wall of confusing codes and numbers. However, these details are the “fingerprint” of your disease. Because Blastic Plasmacytoid Dendritic Cell Neoplasm (BPDCN) is so rare and often looks like other blood cancers, pathologists use a very specific set of markers to ensure they have the right diagnosis [1][2].

The Diagnostic “Triple Threat”

To confirm BPDCN, pathologists look for a specific combination of proteins on the surface of the cancer cells, often called the immunophenotype. For a diagnosis to be solid, the cells must typically test positive for three main markers [3][4]:

  1. CD123: This is the most critical marker. It is highly expressed on BPDCN cells and serves as the “bullseye” for targeted treatments [5][6].
  2. CD4: While often associated with T-cells, this marker is also found on the plasmacytoid dendritic cells where BPDCN begins [3].
  3. CD56: This is a marker typically found on “natural killer” (NK) cells, but its presence alongside CD4 and CD123 is a hallmark of BPDCN [3][4].

Ensuring an Accurate Diagnosis

Because some other leukemias can also show CD4 or CD56, doctors use “tie-breaker” markers to distinguish BPDCN from mimics like Acute Myeloid Leukemia (AML) or Cutaneous T-Cell Lymphoma (CTCL) [7][8]. Two of the most important are:

  • TCF4: This is a “master regulator” protein that is essential for the development of the immune cells involved in BPDCN. Finding TCF4 is highly specific for this disease [9][10].
  • TCL1: This protein is found in almost all BPDCN cases but is usually absent in the mimics that look similar under a microscope [7][11].

If your report mentions that tests for MPO (a marker for AML) or CD3 (a marker for T-cell lymphoma) were negative, this is actually good news—it helps rule out those other diseases and confirms the BPDCN diagnosis [12][3].

What Your Genetics Say

Your report may also include next-generation sequencing (NGS), which looks at the “instruction manual” or DNA of the cancer cells. It is very common to find specific mutations in BPDCN that help confirm how the disease behaves [13][14]:

  • TET2 and ASXL1: These are most common mutations in BPDCN. They affect how genes are turned on and off (epigenetics) [15][16].
  • ZRSR2: This mutation affects how the cell processes genetic information and is a strong indicator of BPDCN [13].
  • MYB: Rearrangements of this gene can drive the growth of BPDCN cells [17].

Why CD123 is the Target

The reason doctors focus so much on CD123 is because it is the target for the main FDA-approved drug for BPDCN, tagraxofusp [5]. Think of CD123 as a specialized docking port on the outside of the cancer cell. The medication is designed to dock exactly at that port, enter the cell, and deliver a payload that stops the cell from making proteins, effectively killing it while sparing many healthy cells that don’t have that “docking port” [18][19]. Finding high CD123 expression on your report is a key step in qualifying for this targeted therapy [6][20].

Common questions in this guide

What does it mean if my report shows CD123, CD4, and CD56?
This combination of protein markers is a hallmark of blastic plasmacytoid dendritic cell neoplasm. Finding all three on the surface of cancer cells helps doctors confirm the diagnosis and separate it from other types of leukemia or lymphoma.
Why is the CD123 marker so important for my treatment?
CD123 acts as a specialized docking port on the outside of BPDCN cells. Testing positive for high levels of this marker is essential because it qualifies patients for the FDA-approved targeted therapy tagraxofusp.
What are TCF4 and TCL1 on my pathology report?
These are specific tie-breaker proteins that confirm a BPDCN diagnosis. Because this rare cancer can look like other leukemias under a microscope, finding TCF4 or TCL1 helps rule out similar diseases like acute myeloid leukemia.
Why does my report mention genetic mutations like TET2 or ASXL1?
Next-generation sequencing checks the DNA of your cancer cells for specific genetic errors. Finding mutations like TET2, ASXL1, or ZRSR2 is common in BPDCN and helps your oncology team understand exactly how your specific disease behaves.
What does it mean if tests for MPO or CD3 are negative?
Negative results for these markers are actually good news for confirming your diagnosis. MPO is a marker for acute myeloid leukemia, and CD3 is a marker for T-cell lymphoma; lacking them helps prove your cancer is BPDCN.

Questions to Ask Your Doctor

Curated prompts to bring to your next appointment.

  1. 1.Does my report show 'triple-positivity' for CD123, TCL1, and TCF4?
  2. 2.Were markers for AML or NK-cell lymphoma, like MPO or CD57, negative to help confirm it is BPDCN?
  3. 3.Which genetic mutations (like TET2, ASXL1, or ZRSR2) were found in my bone marrow or skin biopsy?
  4. 4.What was my CD123 expression level, and how does that influence my eligibility for tagraxofusp?
  5. 5.Does my genetic profile suggest this BPDCN evolved from an underlying condition like MDS?

Questions For You

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References

References (20)
  1. 1

    Blastic plasmacytoid dendritic cell neoplasm with response to pralatrexate.

    Sato S, Tanaka E, Tamai Y

    Annals of hematology 2019; (98(3)):801-803 doi:10.1007/s00277-019-03611-3.

    PMID: 30652209
  2. 2

    Diagnostic approach to blastic plasmacytoid dendritic cell neoplasm: historical perspectives and current understanding.

    Sakamoto K, Takeuchi K

    Journal of clinical and experimental hematopathology : JCEH 2025; (65(1)):1-16 doi:10.3960/jslrt.24069.

    PMID: 40159280
  3. 3

    Spontaneous Regression of Blastic Plasmacytoid Dendritic Cell Neoplasm Following Sepsis by Serratia marcescens: A Case Report and Literature Review.

    Suzuki A, Abe S, Koyama K, et al.

    Internal medicine (Tokyo, Japan) 2021; (60(6)):927-933 doi:10.2169/internalmedicine.5820-20.

    PMID: 33716255
  4. 4

    The Challenge of Diagnosing Acute Myeloid Leukemia or Blastic Plasmacytoid Dendritic Cell Neoplasm: A Case Report.

    Garg S, Dua A, Ansari A, Tabbara I

    Anticancer research 2025; (45(1)):229-233 doi:10.21873/anticanres.17409.

    PMID: 39740819
  5. 5

    Blastic plasmacytoid dendritic cell neoplasm: diagnosis, manifestations, and treatment.

    Sweet K

    Current opinion in hematology 2020; (27(2)):103-107 doi:10.1097/MOH.0000000000000569.

    PMID: 31972688
  6. 6

    Immunotherapies Targeting CD123 for Blastic Plasmacytoid Dendritic Cell Neoplasm.

    Xue T, Budde LE

    Hematology/oncology clinics of North America 2020; (34(3)):575-587 doi:10.1016/j.hoc.2020.01.006.

    PMID: 32336421
  7. 7

    Comparison and Development of Immunohistochemical Diagnostic Criteria for Blastic Plasmacytoid Dendritic Cell Neoplasm.

    Sakamoto K, Baba S, Okumura Y, et al.

    Modern pathology : an official journal of the United States and Canadian Academy of Pathology, Inc 2023; (36(10)):100253 doi:10.1016/j.modpat.2023.100253.

    PMID: 37380058
  8. 8

    Expanding the Immunophenotypic Spectrum of Neoplastic and Reactive Plasmacytoid Dendritic Cells.

    Wu SJ, Sadigh S, Lane AA, Pinkus GS

    American journal of clinical pathology 2023; (159(5)):455-463 doi:10.1093/ajcp/aqac174.

    PMID: 36880313
  9. 9

    An Unexpected Chink in the Transcriptional Armor of Plasmacytoid Dendritic Neoplasms.

    Kleppe M, Levine RL

    Cancer cell 2016; (30(5)):659-660 doi:10.1016/j.ccell.2016.10.016.

    PMID: 27846385
  10. 10

    Dual Expression of TCF4 and CD123 Is Highly Sensitive and Specific For Blastic Plasmacytoid Dendritic Cell Neoplasm.

    Sukswai N, Aung PP, Yin CC, et al.

    The American journal of surgical pathology 2019; (43(10)):1429-1437 doi:10.1097/PAS.0000000000001316.

    PMID: 31261288
  11. 11

    Multi-organ single-cell analysis reveals PLD4 as a biomarker and potential therapeutic target of blastic plasmacytoid dendritic cell neoplasm.

    Wang M, Xue X, Wang Z, et al.

    Cancer cell international 2025; (25(1)):396 doi:10.1186/s12935-025-04038-9.

    PMID: 41219867
  12. 12

    Myeloid Cell Nuclear Differentiation Antigen (MNDA) Expression Distinguishes Extramedullary Presentations of Myeloid Leukemia From Blastic Plasmacytoid Dendritic Cell Neoplasm.

    Johnson RC, Kim J, Natkunam Y, et al.

    The American journal of surgical pathology 2016; (40(4)):502-9 doi:10.1097/PAS.0000000000000595.

    PMID: 26796502
  13. 13

    Integrated Clinical Genotype-Phenotype Characteristics of Blastic Plasmacytoid Dendritic Cell Neoplasm.

    Yin CC, Pemmaraju N, You MJ, et al.

    Cancers 2021; (13(23)) doi:10.3390/cancers13235888.

    PMID: 34884997
  14. 14

    Blastic plasmacytoid dendritic cell neoplasm with genetic mutations in multiple epigenetic modifiers: a case report.

    Dang X, Zhou D, Meng L, Bi L

    The Journal of international medical research 2021; (49(2)):300060520982667 doi:10.1177/0300060520982667.

    PMID: 33530792
  15. 15

    Biallelic TET2 mutations and canonical ASXL1 mutations are frequent and cooccur in Blastic Plasmacytoid Dendritic Cell Neoplasm (BPDCN): An institutional experience and review of literature.

    Zhang X, Hsi ED, Crane GM, Cheng YW

    EJHaem 2023; (4(1)):236-240 doi:10.1002/jha2.617.

    PMID: 36819168
  16. 16

    Localized blastic plasmacytoid dendritic cell neoplasm associated with progressive clonal hematopoiesis and myelodysplastic syndrome.

    Julin C, Nielsen SL, Grantzau TL, et al.

    APMIS : acta pathologica, microbiologica, et immunologica Scandinavica 2025; (133(1)):e13486 doi:10.1111/apm.13486.

    PMID: 39465574
  17. 17

    Single cell sequencing deciphering the heterogeneous landscape of blastic plasmacytoid dendritic cell neoplasm with novel MYB-ZFAT fusion gene.

    Li R, Kuang W, Yang H, et al.

    Cancer cell international 2025; (25(1)):274 doi:10.1186/s12935-025-03899-4.

    PMID: 40691845
  18. 18

    Tagraxofusp, a first-in-class CD123-targeted agent: Five-year postapproval comprehensive review of the literature.

    Jen WY, Konopleva M, Pemmaraju N

    Cancer 2024; (130(13)):2260-2271 doi:10.1002/cncr.35315.

    PMID: 38620053
  19. 19

    Approval of tagraxofusp-erzs for blastic plasmacytoid dendritic cell neoplasm.

    Pemmaraju N, Konopleva M

    Blood advances 2020; (4(16)):4020-4027 doi:10.1182/bloodadvances.2019000173.

    PMID: 32841341
  20. 20

    Current status and future potential of CD123-based targeted therapies for acute leukemia.

    Arslan S, Aribi A, Stein A, Aldoss I

    Expert opinion on biological therapy 2025; (25(12)):1299-1312 doi:10.1080/14712598.2025.2608209.

    PMID: 41431442

This page explains BPDCN pathology and flow cytometry terminology for educational purposes. Your pathologist and oncologist are the best sources for interpreting your specific lab results and diagnostic reports.

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