Stains & molecular markers
PAX5
Copyright: 2002-2021, PathologyOutlines.com, Inc.
PubMed Search: PAX5 [title]
PAX5
Author: Nat Pernick, M.D.
Topic Completed: 1 January 2013
Minor changes: 10 December 2020
Copyright: 2002-2021, PathologyOutlines.com, Inc.
PubMed Search: PAX5 [title]
Table of Contents
Definition / general | Uses by pathologists | Microscopic (histologic) images | Positive staining - normal | Positive staining - disease | Negative staining | Molecular / cytogenetics imagesCite this page: Pernick N. PAX5. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/stainspax5.html. Accessed May 12th, 2021.
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:
Classical Hodgkin lymphoma
Rare PAX5+ anaplastic large cell lymphoma
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
- Most B cell malignancies (pre-B and mature B cell lymphomas / leukemias)
- B cell lymphomas following rituximab therapy
- Hodgkin lymphoma (Reed-Sternberg cells, 97%)
- Lymphoplasmacytic lymphoma
- Merkel cell and small cell carcinoma (93% and 73%, Am J Surg Pathol 2005;29:687)
- High grade neuroendocrine carcinomas (Am J Clin Pathol 2008;129:556, Am J Clin Pathol. 2006;126:798)
Negative staining
- Carcinoid tumor, embryonal carcinoma, myeloma, plasmacytoma, seminoma, T cell lymphoma
Molecular / cytogenetics images
Images hosted on other servers:
Anaplastic large cell lymphomas
