Testicular metastases of prostate cancer are rare, usually clinically silent and present in the late stage of disease. We present the case of a patient with a solitary right testicular metastasis of a prostate cancer Gleason score 5 detected by 18 F Choline PET/CT, 16 yrs after total prostatectomy and 6 yrs after surgery of a left testicular metastasis.

A 80-year-old patient was directed to our department with a biochemically relapse of a prostate carcinoma. He had a laparoscopic prostatectomy in 2000, at age 65. Two 2mm microcarcinomas of prostate cancer at the right base and apex and a left middle carcinoma of 8mm were found. The Gleason score was 5. There was an extracapsular extension and the tumor was classified pT3a. Eight month after surgery the PSA was 0.08ng/ml. In 2004 a rising PSA was observed, 0.48ng/ml, and a salvage prostate bed radiotherapy was performed, with PSA nadir 0.24ng/ml. The patient was then treated with intermittent hormonal therapy until July 2010, when he presented with a large left testicle. The PSA was 2.35ng/ml. The ultrasonography found multiples left testicular nodules. Surgery was performed and histopathology confirmed a 6×4-cm testicular metastasis of the prostate carcinoma with extension to the rete testis and to the epididymis and with lymphatic emboli. Post-surgery the PSA dropped at 0.59ng/ml and 10 months later it was 0.28, with a nadir of 0.21 in November 2011. The patient did not have additional treatment. A new biochemically relapse was diagnosed in March 2016, PSA 5.25ng/ml, PSA DT 3.89 months, velocity 4.03ng/ml/year, and the patient was addressed to our department. F Choline TEP/CT was performed after injection of 165MBq 18 F Choline, 2.9MBq/kg, with a dynamic phase of 10minutes at the pelvis level, followed by an acquisition from the upper thigh to the base of skull.

The 18 F Choline TEP/CT detected a high uptake on the right testicle, SUV max=8, without other suspect lesions. Surgery was performed and the histology confirmed a new 4cm testicular metastasis of the known prostate carcinoma. Post-surgery the PSA level was undetectable.

TEP F Choline is highly reliable in the detection of prostate carcinoma recurrence as in the case we present of a rarely solitary testicular metastasis of prostate cancer Gleason score 5. The testicles have to be well included on PET/CT field of view in order not to overlook such atypical metastases.