Successful Surgical Treatment of Pediatric FUS::TFCP2-Positive Rhabdomyosarcoma of the Mandible: A Case Report.

FUS::TFCP2-positive rhabdomyosarcoma (RMS) is a rare and aggressive subtype that was recently classified as a distinct entity. It is resistant to conventional chemotherapeutic regimens for RMS, and optimal treatment strategies have not been established. Here, we describe an 11-year-old boy with mandibular RMS with a FUS::TFCP2 fusion gene. At the referring hospital, the patient initially underwent standard induction chemotherapy for RMS, but it was ineffective. Radical resection, including segmental mandibulectomy and reconstruction with a rectus abdominis free flap, was performed. Histological examination of the surgical specimen revealed a viable tumor with minimal response to chemotherapy. The patient had remained disease-free for 18 months. Our experience highlights that early pathological diagnosis and prompt surgical intervention for FUS::TFCP2 fusion-positive RMS are crucial due to its chemoresistance.