AMACR (P504S) – α-methylacyl-CoA racemase

AMACR (alpha‑methylacyl‑CoA racemase), also known as P504S, is a mitochondrial and peroxisomal enzyme widely used as an IHC marker in prostate pathology. It shows granular cytoplasmic positivity and is strongly expressed in prostate adenocarcinoma while absent in benign prostate tissue, making it a key marker for diagnosing malignancy. AMACR also demonstrates cytoplasmic expression in several other cancers, including colon adenocarcinoma, ovarian and lung cancers, lymphoma, and melanoma. In IHC, its primary role is to identify prostate carcinoma, typically as part of an antibody panel rather than as a standalone test (1-2).

Recommended Controls

Criteria for acceptable staining is a granular cytoplasmic staining pattern. Normal prostate tissue and prostate cancer is recommended as an inhouse control. A intensely positive cytoplasmic granular reaction in the tumour cells while the epithelial cells in the normal prostate should be negative. Tonsil if used, will not exhibit any staining in the lymphocytes, macrophages or epithelial cells and can be used as a negative control.

Expected staining pattern

Prostate tumour ALK Phos detection kit

Prostate tumour DAB detection kit

Disclaimer

These methods are intended as a guide only. Laboratories that wish to implement these methods should perform internal validation/verification prior to use. The RCPAQAP does not make any claim or warranty for the accuracy or performance of these methods.