Stains
Prostate specific membrane antigen (PSMA)

Author: Sheren Younes, M.D. (see Authors page)

Revised: 17 August 2016, last major update August 2016

Copyright: (c) 2002-2016, PathologyOutlines.com, Inc.

PubMed Search: Prostate specific membrane antigen [title]

Cite this page: Prostate specific membrane antigen (PSMA). PathologyOutlines.com website. http://pathologyoutlines.com/topic/stainspsma.html. Accessed March 26th, 2017.
Definition / General
  • 750 Amino acid, 100 KDa, type II membrane glycoprotein with both folate hydrolase and N-acetylated-alpha-linked-acidic peptidase (NAALAD) activity
  • Assists with folate uptake and modulates excitatory neurotransmissions in brain
  • In contrast to PSA, upregulated with androgen deprivation (Rev Urol. 2004;6 (Suppl 10):S13)
Diagrams / Tables
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PSA vs. PSMA

Uses by Pathologists
  • Tissue PSMA:
    • Expressed in high grade prostatic adenocarcinoma, in contrast to PSA
    • PSMA/PSA ratio by IHC
      • Almost equal in normal prostate
      • Decreased in BPH
      • Increased in prostatic carcinoma; with the highest ratio associated with intratumoral angiogenesis (J Immunoassay Immunochem. 2014;35:48)
  • Staining is associated with high Gleason score (Histol Histopathol 2004 Jul;19:715)
  • PSMA helps identify metastatic prostatic carcinoma in surgical specimens, with higher sensitivity than PSA (Diagn Cytopathol 2014 Jul;42:570), although recommended to combine with a second marker (Mod Pathol 2015 Jan;28:138)
  • Sensitive and specific for prostatic carcinoma versus urothelial carcinoma (Histopathology 2007 Mar;50:472)
  • Interpretation
    • Cytoplasmic or membranous staining
    Micro Images
    Images hosted on Nature.com sever:

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    PSMA and their prostatic markers
    in different prostatic lesions

    Positive Staining - Normal
  • Prostate epithelial cells; also adrenal gland, bladder, breast, esophagus, fallopian tube, kidney, large intestine, liver, ovary, small intestine, spinal cord, stomach, testis
  • Negative Staining - Normal
  • Prostate basal and stromal cells
  • Positive staining - Tumors
  • Prostatic adenocarcinoma
  • Capillary endothelium in ovarian and endometrial carcinoma and cervical squamous carcinoma, providing a role for targeted therapy (Appl Immunohistochem Mol Morphol 2016 Feb 9 [Epub ahead of print])
  • Tumor associated vasculature of primary and metastatic breast carcinoma (APMIS 2014;122:482)