Transvaginal and Transurethral High-Dose-Rate Brachytherapy in a Patient With Malignant Vaginal Melanoma and Urethral Invasion: A Case Report

A 60-year-old woman presented with abnormal genital bleeding. Colposcopy and cystoscopy revealed black pigmented lesions in the vulva, vaginal vestibule, vaginal fornix, external urethral orifice, and urethral mucosa. The patient was diagnosed with vaginal malignant melanoma and urethral invasion. Because the melanoma was confined to the vagina and urethra, high-dose-rate brachytherapy using Ir-192 was selected. Vaginal lesions were irradiated using a vaginal applicator and the urethral lesions were irradiated by inserting a flexible catheter into the urethral catheter. The total radiation dose was 48 Gy in eight fractions. Pembrolizumab was started one month after radiotherapy. All black pigmented lesions disappeared within six months after brachytherapy. There was no sign of recurrence at 15 months after treatment. Adverse events included Grade 2 perivaginal inflammation at 6 weeks after treatment and Grade 3 vaginal stenosis at 15 months after treatment. The combination of intracavitary irradiation using a vaginal applicator and transurethral irradiation using a flexible catheter within a urethral catheter enabled delivery of an adequate tumor dose.