PSMA-Avid Metastatic Prostate Cancer With Intense Penile Uptake on PET/CT: A Rare Site of Spread.

Penile metastasis from prostate adenocarcinoma is an exceptionally rare manifestation of advanced disease. We report the case of a 64-year-old man with biopsy-proven prostatic adenocarcinoma (cT3bN1M1, Gleason 4+4=8), diagnosed in 2020 with an initial PSA of 122.85 ng/mL. The most remarkable finding was intense, diffuse, and homogeneous PSMA uptake throughout the corpora cavernosa along the entire penile shaft (SUVmax=76.9). Histopathologic examination confirmed metastatic prostatic adenocarcinoma (Grade Group 3, Gleason 4+3=7), involving 100% of the sampled penile tissue. This case illustrates an unusual pattern of diffuse penile involvement, likely reflecting advanced hematogenous or retrograde venous dissemination rather than focal metastatic deposits. It underscores the importance of careful evaluation of the external genitalia on PSMA PET/CT and highlights that penile metastases may present as diffuse, highly PSMA-avid infiltration in advanced prostate cancer.