Penile metastasis from prostate cancer with CDK12 mutation: A case report and literature review

There are few reported cases of penile metastasis from prostate cancer. Its clinical presentation can be non-specific, posing diagnostic challenges. A 65-year-old man presented with dysuria in July 2016. Initial evaluation revealed a prostate-specific antigen (PSA) level >500 ng/ml, and magnetic resonance imaging findings suggested advanced metastatic acinar adenocarcinoma (T4N1M1). Pathological examination of a tissue specimen confirmed prostate adenocarcinoma, with a Gleason score of 4+3=7. The patient was started on androgen deprivation therapy with goserelin (10.8 mg every 3 months) and bicalutamide (50 mg once daily), and stable disease was achieved for 66 months. In April 2022, an increased PSA level and a growing penile mass were observed. Prostate-specific membrane antigen positron emission tomography/computed tomography revealed penile metastasis from prostate cancer (PCa). The mass was surgically removed, and pathological examination confirmed infiltrating poorly differentiated PCa. Bicalutamide was replaced by enzalutamide (160 mg once daily) in the treatment regimen. Subsequently, based on the identification of <i>CDK12</i> mutations by genetic testing, treatment with the poly(ADP-ribose) polymerase (PARP) inhibitor olaparib (300 mg twice daily) was initiated. To date, the patient has remained clinically stable with low PSA levels. This case highlights the potential utility of molecular profiling and combined PARP inhibition and androgen receptor-targeting therapy in <i>CDK12</i>-mutated metastatic castration-resistant PCa with rare penile metastasis.