Heterogeneous expression of α-methylacyl-CoA racemase in prostatic cancer correlates with Gleason score

• Published in: Histopathology Vol. 50; no. 2; pp. 243 - 251
• Main Authors: Murphy, A J, Hughes, C A, Lannigan, G, Sheils, O, O'Leary, J, Loftus, B
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01-01-2007; Blackwell
• Subjects: benign prostatic hyperplasia; Biological and medical sciences; Humans; immunohistochemistry; Investigative techniques, diagnostic techniques (general aspects); Male; Medical sciences; Nephrology. Urinary tract diseases; P504S; Pathology. Cytology. Biochemistry. Spectrometry. Miscellaneous investigative techniques; prostatic cancer; Prostatic Neoplasms - diagnosis; Prostatic Neoplasms - enzymology; Prostatic Neoplasms - pathology; Racemases and Epimerases - biosynthesis; Racemases and Epimerases - genetics; Severity of Illness Index; Tumors of the urinary system; Urinary tract. Prostate gland; α-methylacyl-CoA-racemase; Histological grading; Immunohistochemistry; Gleason score; Urinary system disease; Prostate disease; Enzyme; prostatic cancer; P504S; Malignant tumor; a-methylacyl-CoA-racemase; Anatomic pathology; Isomerases; Histopathology; Benign prostatic hyperplasia; α-Methylacyl-CoA racemase; Benign neoplasm; Male genital diseases; Prostate cancer
• ISSN: 0309-0167; 1365-2559
• DOI: 10.1111/j.1365-2559.2007.02572.x

Aims:  α‐Methylacyl‐CoA racemase (AMACR) is a sensitive and specific immunohistochemical marker of prostatic malignancy, staining 80–100% of prostatic cancers with absent staining in benign glands. However, positive staining in benign conditions as well as low rates of AMACR reactivity in prostatic cancer variants have been described. Preliminary use of AMACR immunohistochemistry in our institution has suggested lower specificity and sensitivity for prostatic cancer than initially proposed. The aim of this study was to establish true rates of AMACR reactivity in prostatic cancer and benign prostatic hyperplasia (BPH).
Methods and results:  AMACR immunohistochemistry was performed on sections from 57 prostatic cancers and 44 BPH resections. Ninety‐one percent of cancers were AMACR+, with diffuse (> 75%) tumour staining in 53% of cases. Thirty‐eight percent of tumours showed heterogeneous expression (1–75% tumour staining). This was significantly correlated with increased Gleason score. High‐grade prostatic intraepithelial neoplasia (PIN) was AMACR+ in 87% of cancers. Eleven percent of BPH showed moderate or strong staining in benign glands, focally mimicking the malignant staining pattern.
Conclusions:  This study confirms heterogeneous AMACR expression in prostatic cancer and shows a correlation with Gleason score. Positive staining in BPH is also documented, thus emphasizing the importance of interpreting AMACR immunohistochemistry in the context of other findings in a diagnostic setting.