Stains & molecular markers
AMACR


Topic Completed: 6 May 2020

Minor changes: 8 September 2020

Copyright: 2003-2020, PathologyOutlines.com, Inc.

PubMed Search: AMACR[title]

Iryna Samarska, M.D., Ph.D.
Jonathan Epstein, M.D.
Page views in 2019: 19,264
Page views in 2020 to date: 14,470
Cite this page: Samarska I, Epstein J. AMACR. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/stainsamacr.html. Accessed September 21st, 2020.
Definition / general
  • Alpha methyacyl CoA racemase (AMACR) is a mitochondrial and peroxisomal enzyme, a 382 amino acid protein essential in lipid metabolism, encoded by a 1621 bp sequence gene, located on chromosome 5p13 (J Clin Pathol 2003;56:892)
  • One of the most widely used markers of prostate carcinoma, because this protein is upregulated in prostate carcinoma and not found in benign prostate tissue (J Clin Pathol 2003;56:892, Am J Surg Pathol 2014;38:e6)
Essential features
  • Cytoplasmic expression is seen in prostate adenocarcinoma (80%), colon adenocarcinoma (90%) and in many other cancers, including ovarian, lung cancers, lymphoma and melanoma (Am J Surg Pathol 2002;26:926)
Terminology
  • P504S (antibody against AMACR)
Pathophysiology
  • AMACR catalyzes the racemization of alpha methyl branched carboxylic coenzyme A thioesters and this enzyme is essential in the oxidation of bile acid intermediates and branched chain fatty acids (J Clin Pathol 2003;56:892)
  • Phytanic acid, present in red meat and dairy products, is one of the primary substrates of AMACR and has been found to be elevated in prostate adenocarcinoma (Prostate 2011;71:498)
  • AMACR is important in the pharmacological activation of ibuprofen and related drugs (Bioorg Chem 2019;92:103264)
Clinical features
  • Adult onset sensory motor neuropathy is developed due to mutations in the AMACR gene, associated with reduced enzyme activity (J Clin Pathol 2003;56:892)
  • Diets rich in dairy products and red meat increases the risk for developing prostate cancer, because dairy products and red meat are the major dietary sources of the branched chain fatty acid substrates of AMACR / P504S (J Clin Pathol 2003;56:892)
  • AMACR gene polymorphisms (D175G and M9V polymorphisms) are thought to affect the expression of the enzyme and might be risk factors for prostate cancer (Asian Pac J Cancer Prev 2015;16:1857, Prostate 2008;68:1373)
Interpretation
  • Cytoplasmic granular staining pattern
Uses by pathologists
Prognostic factors
Microscopic (histologic) images

Contributed by Jonathan Epstein, M.D., Debra Zynger, M.D.

Prostate adenocarcinoma, triple stain

RCC papillary type 1 with AMACR

Positive staining - normal
  • Kidney:
  • GI / liver:
    • Hepatocytes and epithelium of the gastrointestinal tract show moderate cytoplasmic staining
Positive staining - disease
Negative staining
Board review style question #1
Biopsy of a lymph node shows metastasis of an unknown tumor. Which immunohistochemical panel is consistent with primary prostate carcinoma?

  1. AE1 / AE3-, S100+, MelanA+, AMACR+
  2. AMACR+, CDX2+, CK20+
  3. AMACR+, p63-, HMWCK-, NKX3.1+
  4. AMACR+, p63+, HMWCK+, NKX3.1-
Board review answer #1
C. AMACR+, p63-, HMWCK-, NKX3.1+

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Reference: AMACR
Board review style question #2

Transurethral resection of the urinary bladder reveals a neoplastic proliferation, composed of small glandular structures, which are positive for AMACR and NKX3.1. What is the diagnosis?

  1. Adenocarcinoma of the urinary bladder, intestinal type
  2. Clear cell adenocarcinoma urinary bladder
  3. Invasive urothelial carcinoma
  4. Prostate adenocarcinoma (metastatic or direct invasion)
Board review answer #2
D. Prostate adenocarcinoma (metastatic or direct invasion)

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Reference: AMACR
Board review style question #3

Biopsy of the paraaortal lymph node of a 60 year old man shows metastatic tumor (figure A), which is positive for 34 beta E12 (figure B) and AMACR (figure C) but negative for NKX3.1 (figure D). The tumor is also positive for GATA and CK7 (not shown) but negative for CDX2 (not shown). What is the diagnosis?

  1. Metastatic colorectal adenocarcinoma
  2. Metastatic prostate adenocarcinoma
  3. Metastatic squamous cell carcinoma
  4. Metastatic urothelial cell carcinoma
Board review answer #3
D. Metastatic urothelial cell carcinoma

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Reference: AMACR
Board review style question #4

In the resection specimen of the urinary bladder of a 60 year old man with known invasive high grade urothelial cell carcinoma and multifocal carcinoma in situ, a glandular and cystic lesion was found under the urothelial lining (see image). The lesion is positive for PAX8 and AMACR. What is the diagnosis?

  1. Invasive urothelial cell carcinoma
  2. Metastatic colorectal adenocarcinoma
  3. Metastatic prostate adenocarcinoma
  4. Nephrogenic adenoma
Board review answer #4
D. Nephrogenic adenoma

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Reference: AMACR
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