Postoperative brachytherapy for vaginal rhabdomyosarcoma in an infant using a custom 3d-printed applicator.

Abstract

Introduction Tumours of the female genital tract are rare in children. Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma of childhood an often occurs in the genitourinary tract. RMS treatment is multimodal, involving multiagent chemotherapy and local therapy - radiation therapy, surgery or both - with the aim of preservation of form, function and quality of life. This report describes the management of a 9- month-old with localised embryonal/FOXO1-negative RMS arising from the vagina. Methods The initial 7.2cm tumour reduced to 5cm with neoadjuvant chemotherapy prior to interval R1 debulking surgery. A multistage process was undertaken to create a customised vaginal applicator. Detailed measurements at the time of surgery were taken and several weeks later a vaginal impression made with dental polyvinylsiloxane silicone. These were used to create a digital 3D applicator model with channels designed to deliver optimal treatment to the tumour whilst reducing dose to the uninvolved vagina. An MRI scan with the printed applicator in situ was used to create a final plan for brachytherapy. Results A four-channel applicator was 3D printed using a biocompatible medical resin. High dose rate brachytherapy was delivered as an outpatient with daily general anaesthetic and ultrasound guidance for insertion. The clinical target volume D90 received 42 Gy (EQD210) in five fractions. There was no acute toxicity reported. Conclusion/Implications Brachytherapy is a highly specialised technique offering both organ preservation and dose conformity to minimise late toxicity. (Figure Presented).