Stains
PAX5


Topic Completed: 1 January 2013

Revised: 7 March 2019

Copyright: 2002-2015, PathologyOutlines.com, Inc.

PubMed Search: PAX5 [title]

Nat Pernick, M.D.
Page views in 2018: 8,359
Page views in 2019 to date: 5,309
Cite this page: Pernick N. PAX5. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/stainspax5.html. Accessed July 19th, 2019.
Definition / general
  • Also called BSAP, a B cell-lineage specific activator protein at 9q13
  • Member of paired box (PAX) family of transcription factors, which have a novel, highly conserved DNA-binding motif, known as the paired box
    • Encodes BSAP expressed at early stages of B-cell differentiation, also in developing CNS and testis (Wikipedia - PAX5)
  • Detected in B cells from pro-B cell stage to plasma cell stage where it is downregulated (Clin Med Res 2010;8:84)
  • Required for progression of B cell development beyond the early pro-B cell stage (Cancer Res 2011;71:7345)
Uses by pathologists
  • Detection of pre-B cells (PAX5+, more sensitive and specific than CD20)
  • Diagnosis of Reed-Sternberg cells in classic Hodgkin lymphoma (PAX5+) versus T / null cell anaplastic large cell lymphoma (PAX5-, although rarely positive in T cell lymphomas, Mod Pathol 2010;23:593)
  • Diagnosis of lymphoplasmacytic lymphoma / plasmacytoid differentiation in marginal zone lymphoma (PAX5+) versus plasmacytoma (PAX5-, Am J Surg Pathol 2002;26:1343)
Microscopic (histologic) images

Images hosted on Other servers:

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Classical Hodgkin lymphoma

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Rare PAX5+ anaplastic large cell lymphoma

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Uterus (endometrium), mesonephric adenocarcinoma

Positive staining - normal
  • B cells from pro-B cell stage to plasma cell stage, where it is down regulated
Positive staining - disease
Negative staining
  • Carcinoid tumor, embryonal carcinoma, myeloma, plasmacytoma, seminoma, T cell lymphoma
Molecular / cytogenetics images
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Anaplastic large cell lymphomas

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