Stains & CD markers
CD45 (LCA)

Resident / Fellow Advisory Board: Mario L. Marques-Piubelli, M.D.
Editorial Board Member: Christian M. Schürch, M.D., Ph.D.
Elena M. Fenu, M.D.
Danielle Lameirinhas Vieira Maracaja, M.D.

Last author update: 1 February 2022
Last staff update: 1 February 2022

Copyright: 2003-2024,, Inc.

PubMed Search: CD45 [title] review [ptyp]

Related topics: CD45RO, CD45RA, CD45RB, CD45RC

Elena M. Fenu, M.D.
Danielle Lameirinhas Vieira Maracaja, M.D.
Page views in 2023: 28,299
Page views in 2024 to date: 14,756
Cite this page: Fenu EM, Maracaja DLV. CD45 (LCA). website. Accessed July 13th, 2024.
Definition / general
  • Ubiquitous cell surface marker of nucleated hematopoietic cells involved in the regulation and activation of the immune system
  • Detectable by immunohistochemistry or flow cytometry
Essential features
  • Receptor tyrosine phosphatase protein expressed on the cell surface of white blood cells and involved in B and T cell activation and signaling (Immunol Lett 2018;196:22)
  • Used by pathologists to highlight inflammatory cells or determine the hematopoietic nature of tumors of unknown origin with high specificity
  • Leukocyte common antigen (LCA) or Ly-5
  • High molecular weight (180 - 220 kDa) transmembrane protein with intrinsic tyrosine phosphatase activity
  • Involved in regulating thymic selection and B and T cell antigen receptor mediated activation (Hum Pathol 2017;62:83)
Clinical features
  • Membranous / cytoplasmic staining
Uses by pathologists
Prognostic factors
Microscopic (histologic) images

Contributed by Elena M. Fenu, M.D.
Anaplastic large cell lymphoma Anaplastic large cell lymphoma

Anaplastic large cell lymphoma

Diffuse large B cell lymphoma Diffuse large B cell lymphoma

Diffuse large B cell lymphoma

Plasmablastic lymphoma Plasmablastic lymphoma

Plasmablastic lymphoma

Leukemia cutis Leukemia cutis

Leukemia cutis

Positive staining - normal
  • White blood cells, including granulocytes, lymphocytes, eosinophils, basophils (dim), monocytes, macrophages / histiocytes, mast cells and plasma cells; not including red blood cells and their precursors, megakaryocytes or platelets (Immunol Lett 2018;196:22)
Positive staining - disease
Negative staining
Sample pathology report
  • Lymph node, right cervical excision:
    • Nodular lymphocyte predominant Hodgkin lymphoma (see comment)
    • Comment: There is total replacement of the nodal architecture by expansive vague nodules of small lymphocytes with sparse, relatively large tumor cells with multilobulated or round nucleus, thin nuclear membrane, finely granular chromatin and variable, small nucleoli (popcorn cells). The tumor cells are immunoreactive for CD45, CD20 and CD19 and negative for CD15 and CD30, which confirms the diagnosis.
Board review style question #1

CD45 expression is consistently seen in most hematopoietic neoplasms and it is considered a specific marker when investigating neoplasms of unknown primary origin; however, CD45 can be negative in a subset of hematopoietic neoplasms. Which of the following hematopoietic neoplasms is positive for CD45 in nearly all cases?

  1. Acute megakaryoblastic leukemia
  2. B lymphoblastic leukemia / lymphoma (B-ALL)
  3. Classic Hodgkin lymphoma (CHL)
  4. Nodular lymphocyte predominant Hodgkin lymphoma (NLPHL)
  5. Plasma cell neoplasm
Board review style answer #1
D. Nodular lymphocyte predominant Hodgkin lymphoma (NLPHL). CD45 is positive in nearly all cases and it is an important marker together with other B cell markers (CD20, PAX5, CD19, CD79a, CD75, OCT2 and BOB1) in differentiating classic Hodgkin lymphoma (CHL) and NLPHL. Sometimes the background staining of the hematopoietic cells can make the interpretation of CD45 difficult; however, the absence of staining in back to back Reed-Sternberg / Hodgkin cells or consistent positive staining in lymphocyte predominant (LP) cells are helpful in the differentiation of these lesions. All the other hematopoietic neoplasms listed on the question can have negative expression of CD45.

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Reference: CD45
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