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Table of Contents
Definition / general | Uses by pathologists | Microscopic (histologic) images | Positive stains | Negative stainsCite this page: AMACR. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/stainsamacr.html. Accessed July 12th, 2017.
Definition / general
- Alpha Methyl Acyl Coenzyme A Racemase; also called P504S
- Identified from prostate adenocarcinoma by cDNA library subtraction, coupled with high throughput microarray screening of human prostatic tissue
- A mitochondrial and peroxisomal enzyme involved in beta-oxidation of dietary branched-chain fatty acids and fatty acid derivatives (including bile acid intermediates)
- AMACR deficiency is rare cause of cerebellar ataxia (Neurology 2011;76:1768)
Uses by pathologists
- Cytoplasmic immunohistochemical stain
- Sensitive (82-100%) and relatively specific (70-100%) for prostate carcinoma vs. benign prostate (Am J Surg Pathol 2001;25:1397, Am J Surg Pathol 2002;26:1588, Am J Clin Pathol 2004;122:275)
- Staining is strongly positive and usually diffuse, regardless of Gleason grade
- Less sensitive for prostatic adenocarcinoma in Japanese patients (Prostate 2013;73:54)
- Most specific if circumferential luminal to subluminal and diffuse cytoplasmic staining
- Benign prostate is usually negative or only focal / weakly positive; however, partial atrophy and crowded benign glands may be positive (Am J Surg Pathol 2005;29:874)
- Identify small foci of prostatic adenocarcinoma, in conjunction with 34betaE12 or p63 (Am J Surg Pathol 2002;26:1169)
- Used with triple stain (PIN4 cocktail; p63 and 34betaE12-Am J Clin Pathol 2005;123:231) or in various combinations of other markers (with CK5/6-Am J Clin Pathol 2009;132:211; with p63 for destained H&E-stained sections (Am J Clin Pathol 2005;124:708)
- Triple stain has increased specificity for detecting prostatic adenocarcinoma in limited needle biopsy material (Diagn Pathol 2012;7:81)
- Triple stain may be helpful in assessing crushed surgical margins and can provide a cost effective way of evaluating abnormal glandular foci in addition to maximizing the use of small tissue samples (J Clin Pathol 2012;65:437, Am J Clin Pathol 2007;127:248)
- May identify a subset of atypical adenomatous hyperplasia of the prostate with a premalignant potential (Am J Surg Pathol 2002;26:921)
Microscopic (histologic) images
Images hosted on other servers:
Colonic adenoma
Quality control for AMACR staining
Prostate-
Adenosis
High grade PIN
Suspicious for adenocarcinoma
Adenocarcinoma
Adenocarcinoma
Adenocarcinoma
Positive stains
- Prostate:
- Adenocarcinoma and high grade PIN
- Partial prostatic atrophy and crowded benign prostatic glands may be positive (Am J Surg Pathol 2005;29:874)
- Bladder:
- Nephrogenic adenoma (78%) and prostate adenocarcinoma (96%), use S100A1 to distinguish (Beijing Da Xue Xue Bao 2013;45:522)
- Urothelial carcinoma (31%, Hum Pathol 2003;34:792)
- Colon:
- colon adenomas with high grade dysplasia (63%) (World J Gastroenterol 2010;16:2476)
- colorectal carcinoma (Am J Surg Pathol 2002;26:926)
- Esophagus: Barrett related dysplasia (93%-high grade, 44%-low grade, Appl Immunohistochem Mol Morphol 2008;16:447)
- Kidney: renal cell carcinoma-papillary type (75-83%, Hum Pathol 2003;34:792, World J Urol 2013;31:847)
- Liver: dysplasia and hepatocellular carcinoma (Appl Immunohistochem Mol Morphol 2006;14:411, Hum Pathol 2003;34:792)
- Skin: extramammary Paget disease (71%, Am J Clin Pathol 2007;127:567)
- Stomach: adenocarcinoma (27%, Hum Pathol 2003;34:792, Int J Clin Exp Pathol 2008;1:518)
- Also carcinomas of breast, cervix, lung, ovary; melanoma (Am J Surg Pathol 2002;26:926)
Negative stains
- Prostate: benign (usually, see exceptions above), atypical adenomatous hyperplasia (usually, 10% are positive, Am J Surg Pathol 2002;26:921)
- Bowel, normal (large, small), small intestinal adenocarcinoma (usually, 4-6% are positive, Am J Surg Pathol 2005;29:890)
- Ovarian carcinoma (usually, 10% are positive, Virchows Arch 2011;459:91)
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