In the era of multiparametric prostate MRI (mpMRI), differentiation of GnP from prostate cancer on imaging is essential.<h4>Case presentation</h4>We report a case of post-BCG GnP in a patient with nonmuscle invasive bladder cancer, presenting with a prostate-specific antigen level of 21.6 ng/ml and prostate imaging reporting and data system (PI-RADS) 5 peripheral lesions. This evidence concerns the gene KLK3 and prostate cancer.