α-Methylacyl CoA racemase (P504S):: overview and potential uses in diagnostic pathology as applied to prostate needle biopsies

The diagnosis of prostatic adenocarcinoma remains dependent on the recognition of basic haematoxylin and eosin criteria. The discovery of alpha-methylacyl CoA racemase/P504S (AMACR/P504S) overexpression in prostate cancer represents a triumph of high throughput microarray technology, and is a powerful demonstration of how this methodology can be used to facilitate the rapid development of diagnostically relevant antibodies. Immunohistochemistry with anti-AMACR/P504S is useful for detecting prostate cancer in the full range of prostate specimens encountered in surgical pathology, be they needle biopsies, transurethral resection of prostate chips, or prostatectomies. In particular, studies to date with AMACR/P504S clearly demonstrate the ability of this marker to support a diagnosis of malignancy in prostate needle biopsies. This is particularly true when it is combined with negative staining for a basal cell marker, such as 34betaE12 or p63. Although it has limitations with respect to sensitivity and specificity, AMACR/P504S will no doubt become a standard adjunctive stain used by pathologists seeking to reach a definitive diagnosis in prostate biopsies considered to be atypical, but not diagnostic of malignancy on haematoxylin and eosin sections alone.