Stains & CD markers

Editorial Board Members: Christian M. Schürch, M.D., Ph.D., Patricia Tsang, M.D., M.B.A.
Narittee Sukswai, M.D.
Joseph Khoury, M.D.

Last author update: 15 August 2022
Last staff update: 15 August 2022

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PubMed Search: CD123

Narittee Sukswai, M.D.
Joseph Khoury, M.D.
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Page views in 2023 to date: 4,682
Cite this page: Sukswai N, Khoury J. CD123. website. Accessed September 25th, 2023.
Definition / general
  • Interleukin 3 receptor alpha chain (IL3Rα)
  • Upregulated and overexpressed in a variety of myeloid and lymphoid neoplasms
  • CD123 is a biomarker for targeted therapy
Essential features
  • CD123 serves as a diagnostic, prognostic and therapeutic marker in some hematologic malignancies, especially acute leukemia
  • CD123 and TCF4 coexpression by immunohistochemistry is highly specific and sensitive for blastic plasmacytoid dendritic cell neoplasm (BPDCN)
  • Tagraxofusp (SL-401) is a CD123 targeted therapy for BPDCN
  • IL3Rα
  • Membrane receptor that heterodimerizes with the β common (βc) subunit to constitute the functional IL3 receptor (IL3R)
  • IL3R is the IL3 specific member of the beta βc family of receptors, which also includes IL5R and granulocyte monocyte colony stimulating factor (GM CSF) receptor
  • Functions in regulating growth, proliferation, survival and differentiation of hematopoietic cells, along with immunity and inflammatory response
  • Downstream signaling is primarily through JAK / STAT, RAS / MAPK and phosphatidylinositol 3 kinase pathways (Cancers (Basel) 2020;12:3087)
Clinical features
  • Strongest level of CD123 staining is on plasmacytoid dendritic cells
  • CD123 is expressed by endothelial cells
  • CD123 is a membrane bound protein, resulting in a membranous pattern of staining by immunohistochemistry and surface expression by flow cytometry
  • CD123 expression in normal karyotype AML is associated with FLT3-ITD and NPM1 mutations (Br J Haematol 2020;188:181)
  • Reference: Am J Surg Pathol 2019;43:1429
Uses by pathologists
Prognostic factors
  • Prognostic impact of CD123 expression has not been established
Microscopic (histologic) images

Contributed by Joseph Khoury, M.D.


Blastic plasmacytoid dendritic cell neoplasm

Blastic plasmacytoid dendritic cell neoplasm

Positive staining - normal
  • Hematopoietic stem cells
  • Endothelial cells
  • Plasmacytoid dendritic cells
Positive staining - disease
Negative staining
Board review style question #1
Patient presents with a skin tumor comprised of blastoid neoplastic cells involving the dermis and subcutaneous tissue without epidermotropism. Which immunohistochemical profile suits the diagnosis of blastic plasmacytoid dendritic cell neoplasm?

  1. AE1 / AE3 positive, chromogranin positive
  2. CD21 positive, CD23 positive
  3. CD34 positive, MPO positive
  4. TCF4 / CD123 positive, CD4 positive, CD56 positive, CD303 positive
Board review style answer #1
D. TCF4 / CD123 dual expression is highly sensitive and specific for blastic plasmacytoid dendritic cell neoplasm. Such staining is rarely encountered in other malignancies.

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Reference: CD123
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