Penile Metastasis From Dedifferentiated Prostate Cancer With Low PSA Levels: A Case Report.

Penile metastasis from prostate cancer is rare and is associated with a poor prognosis; however, there is currently a lack of high-level evidence to guide the management of this condition. This case report describes a 68-year-old male with prostate cancer who developed a penile metastasis during follow-up. This occurred despite stable prostate-specific antigen (PSA) levels after treatment with androgen deprivation therapy, combined with endocrine therapy and radiotherapy. Imaging studies and intraoperative frozen section pathology suggested a penile tumor. The patient subsequently underwent total penectomy combined with urinary diversion surgery. Postoperative histopathology confirmed poorly differentiated adenocarcinoma consistent with metastatic prostatic adenocarcinoma exhibiting morphological changes related to prior therapy. This case highlights the importance of maintaining clinical suspicion for penile metastasis in prostate cancer patients with stable PSA levels, especially in the context of tumor dedifferentiation, to facilitate early diagnosis and appropriate intervention.