Seed lost to perineum from hydrogel spacer after brachytherapy for prostate cancer.

Introduction: We describe a rare case of brachytherapy for prostate cancer in which a seed was lost from the perineum after a hydrogel injection.

Case Presentation: A 71-year-old Japanese man was diagnosed with localized high-risk prostate cancer. Trimodality therapy with I-125 brachytherapy was selected, and combined androgen blockade therapy was initiated. Brachytherapy and hydrogel injection were performed 7 months after combined androgen blockade initiation; 6 months later, the patient visited our hospital with complaints of redness and bleeding in the perineum. Serous effusion and loss of a seed on the right side of the perineal anus were observed. Pelvic magnetic resonance imaging showed a tunnel like discharge of hydrogel from the dorsal prostate to the perineum. The fistula was incised, the seed was removed, and drainage was performed.

Conclusion: Appropriate diagnosis and treatment with careful follow-up are required in patients at high risk of infection after brachytherapy with hydrogel injection.