Diagnostic Value of ERG in Prostate Needle Biopsies Containing Minute Cancer Foci

Background: Prostate carcinoma (PC) is the second most diagnosed cancer in men population worldwide. The small amount of the tissue in prostate needle biopsy is often sufficient for the correct interpretation. Novel antibodies, as ERG, could add to the diagnostic value of IHC study in analysing difficult core biopsies. Aim: The aim of the present study was to establish a diagnostic use of ERG in a work-up of prostate needle biopsies containing minute PC, individually and in combination with AMACR/34βE12. Materials and methods: From total number of 1710 consecutive prostate needle biopsies based on HE stain 114 biopsies containing minute PC. Selected biopsies were incubated with anti-ERG, AMACR and 34βE12 antibodies using immunohistochemical technique. Results: Among 98 selected biopsies, 57 showed positive and 41 negative ERG staining. AMACR staining was positively expressed in 86 of the cases and completely absent in remaining 12. In 9 of the AMACR-negative cases the final diagnosis was establish by manifestation of ERG expression in the tumour foci. 95 of the biopsies demonstrated lack of 34βE12 expression and only 3 cases showed weak patchy staining. Among these cases 2 were ERG-positive. Conclusion: ERG antibody could be especially helpful in the cases with controversial expression of AMACR and 34βE12.