Brachytherapy seeds as a nidus for urethral stone formation: A case report

Iatrogenic foreign bodies can cause urolithiasis. However, iodine seeds used in brachytherapy are not a known cause of stone formation. We report a rare case of urethral stone formation with brachytherapy seeds determined to be the nidus, which occurred 9 years after permanent seed brachytherapy for prostate cancer.

An 87-year-old man with a history of prostate cancer treated with brachytherapy presented to our hospital with macroscopic hematuria. He underwent transurethral resection of the mucosa with erythema 4 years after brachytherapy. Cystoscopy revealed urethral stones on the bladder neck. Transurethral lithotripsy was performed and the nidus of stone formation was revealed to be an aggregate of iodine seeds.

In the course of the long-term follow-up after brachytherapy for prostate cancer, the possibility of the formation of the urethral stone associated with iodine seeds should be considered when gross hematuria is observed.