Diagnostic utility of immunohistochemical markers alpha methyl acyl coA racemase (AMACR) and Ets related gene (ERG) in prostate cancer.

Objectives: To study the sensitivity and specificity of IHC markers AMACR and ERG in prostatic adenocarcinoma.

Methods: The study was a prospective one and samples were collected from August 2014 to June 2016. A total of 186 samples were obtained from the Department of Urology, in which 112 of these were benign prostatic hyperplasia (BPH), and 71 were prostatic adenocarcinoma. The adenocarcinoma cases were evaluated by two histopathologists, and appropriate Gleason score was given according to the modified ISUP Gleason grading system (2016). IHC markers AMACR & ERG were performed on the adenocarcinoma cases and their sensitivity and specificity were calculated.

Results: AMACR was a highly sensitive and specific marker for detecting prostatic carcinoma with a sensitivity and specificity of 95.8% and 96.5% respectively. ERG was a very specific marker with poor sensitivity in detecting prostate cancer. The sensitivity and specificity of ERG were 35.2% and 100% respectively. ERG expression decreased with increasing Gleason grade, PSA level, and tumour volume, which was statistically significant while the association of AMACR with Gleason grade or with tumor volume was not significant.

Conclusion: ERG is a marker of early prostatic carcinogenesis and tumors may be positive or negative subtypes. Special histomorphologic features like perineural invasion, glomerulations, and intraluminal blue mucin were also studied. AMACR was a highly sensitive marker for detecting prostatic adenocarcinoma, while ERG was highly specific.