• Racemase
  • P504S


Technical InfoEdit

Alpha-methylacyl-CoA racemase, also known as AMACR, is a protein which in humans is encoded by the AMACR gene.

Staining PatternEdit

Cytoplasmic, granular.

Expression in Normal TissuesEdit

  • Distal convoluted renal tubules[1]

Expression in Neoplastic EntitiesEdit

Tumor name % Positive Staining Number of Cases

Intermediate/Uncertain Malignant PotentialEdit
Tumor name % Positive Staining Number of Cases
Prostatic Intraepithelial Neoplasia (PIN)
Tumor name % Positive Staining Number of Cases
Prostatic adenocarcinoma
Papillary Renal Cell Carcinoma (RCC) (type 1 and 2)
Mucinous, Tubular, and Spindle Cell Carcinoma of the kidney
Colorectal adenocarcinoma

Expression in Non-Neoplastic EntitiesEdit

  • Nephrogenic adenoma: 58% (22/38 cases)[1]
  • Partial atrophy: 79% (15/19 cases)[2]

Pertinent NegativesEdit

This antigen is typically NOT expressed by the following entities:

Practical Uses / PanelsEdit

  • Can be used to differentiate between prostatic adenocarcinoma (strongly and diffusely positive) from benign prostatic tissue (negative/weakly and/or focally positive [crowded benign glands or atrophic glands may be positive])[2]

Common PitfallsEdit

AMACR can stain partial atrophy and small foci of crowded glands which may lead to overdiagnosis of prostatic adenocarcinoma.[2] AMACR fails to stain up to 65% of foamy, atrophic and pseudohyperplastic adenocarcinomas.

Related Links/Other ResourcesEdit


  1. 1.0 1.1 Am J Surg Pathol. 2004 Sep;28(9):1224-9.
  2. 2.0 2.1 2.2 Am J Surg Pathol 2005 Jul;29(7):874-80.
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