A rare case of isolated castrate resistant bilateral testicular metastases in advanced prostate cancer

Testicular metastasis is rare with the prostate being the most common site of primary cancer. We report a case of a 72-year-old man with castration-resistant prostate cancer (CRPC) and known metastases to bone and lymph nodes, who developed bilateral painful swollen testes 3 years after the initial diagnosis of prostate cancer. He had first presented with lower urinary tract symptoms (LUTS) with suspicious findings on digital rectal examination of the prostate, and an elevated serum prostate specific antigen (PSA) level of 129 ng/mL. Transrectal prostate biopsy revealed Gleason 4 + 5 adenocarcinoma. Radiological staging showed locally advanced prostate cancer with extensive metastases to bone and pelvic and retroperitoneal lymph nodes. He was given hormonal therapy for over 2 years until progression to CRPC. Six months later he developed painful bilateral testicular swellings, and serum markers for testicular germ cell cancer were normal. Bilateral orchiectomy was performed, showing metastatic prostate cancer (Gleason 4 + 5) on histology. One month postoperatively his PSA level dropped to 0.1 ng/mL from a presurgery level of 6.24 ng/mL.