ERG and prostate intraepithelial neoplasia: IDC‐P has been reported to exhibit a higher prevalence of TMPRSS2‐ERG fusions than prostatic intraepithelial neoplasia (PIN),25, 26 but the rate seems to be similar between IDC‐P and concurrent invasive carcinoma,27, 28, 29 and therefore a clonal relationship between IDC‐P and prostate is inferred based on this similar TMPRSS2‐ERG rate by some studies.