Heterogeneous expression of alpha-methylacyl-CoA racemase in prostatic cancer correlates with Gleason score.
OBJECTIVE
Alpha-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).


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.
Murphy
A J
AJ
Department of Cellular Pathology, Adelaide and Meath Hospital, Dublin, Ireland.
Hughes
C A
CA
Lannigan
G
G
Sheils
O
O
O'Leary
J
J
Loftus
B
B
D006801:Humans; D008297:Male; D011471:Prostatic Neoplasms / Q000175:diagnosis* / Q000201:enzymology* / Q000473:pathology; D019998:Racemases and Epimerases / Q000096:biosynthesis* / Q000235:genetics*; D012720:Severity of Illness Index
D019998:Racemases and Epimerases; C108352:alpha-methylacyl-CoA racemase