Prostate brachytherapy seed migration to a left varicocele

Purpose: To report a rare case of seed migration to a left varicocele after transperineal interstitial prostate brachytherapy with loose iodine-125 (¹²⁵I) seeds. Methods and Materials: A 73-year-old man presented with a serum prostate-specific antigen level of 5.21ng/mL, Gleason score of 7 (3+4), and clinical T1c adenocarcinoma of the prostate. The patient underwent transperineal interstitial prostate brachytherapy with loose ¹²⁵I seeds followed by external beam radiation therapy. Two weeks after seed implantation, a followup pelvic radiograph was obtained. One month after seed implantation, a pelvic computed tomography scan for postimplant dosimetric analysis was carried out. Subsequent ultrasound examination of the scrotum was undertaken. Results: Two weeks after seed implantation, an anteroposterior pelvic radiograph showed that a migrated seed was overlapped by the scrotum. Postimplant pelvic computed tomography revealed that a seed had migrated to the left side of the scrotum. Subsequent ultrasound examination of the scrotum revealed that the patient had a left varicocele to which the seed had migrated. The patient had no symptoms related to the migrated seed. Conclusions: This is the first report of seed migration to a left varicocele after transperineal interstitial prostate brachytherapy with loose ¹²⁵I seeds. For the present case, we suggest that the seed moved from the prostate to the left varicocele through the pelvic veins, bypassing the systemic circulation.