A seed link connector protruding into the bladder formed a bladder stone.

Introduction: Low-dose-rate brachytherapy is performed for localized prostate cancer. We report the first case of a bladder stone encompassing the seed migrated into the bladder in a patient treated with low-dose-rate brachytherapy.

Case Presentation: A man was diagnosed with prostate cancer and underwent low-dose-rate brachytherapy. After 2 months, dysuria occurred, and ultrasonography revealed a needle-shaped high-intensity protruding from the prostate into the bladder. Cystoscopy examination found a seed link connector. With the possibility of natural dissolution of the seed link, careful observation was chosen. However, 16 months later, hematuria occurred, and an X-ray revealed a bladder stone encompassing the seed. Compared with the X-ray right after seeding, the seed located near the right bladder neck had fallen. The seed was removed by transurethral bladder lithotripsy.

Conclusion: Seeds should be carefully located within the prostate, otherwise a bladder stone may be formed encompassing the seed.