Carbon ion radiotherapy and AI chemotherapy for soft tissue sarcoma of the temporomandibular joint: A case report of 5-year disease-free survival without wide resection.

We report a case of soft tissue sarcoma (STS) arising in the temporomandibular joint (TMJ), a rare site associated with considerable functional and aesthetic challenges when resection is required. A 33-year-old female with neurofibromatosis type 1 presented with progressive swelling in the right TMJ. Imaging revealed an enlarging, irregular region. Histopathological findings were suggestive of a high-grade STS, but definitive subclassification was not possible. The patient declined surgery due to potential facial nerve injury and cosmetic concerns. As an alternative, a combination of carbon ion radiotherapy and AI chemotherapy (ifosfamide and doxorubicin) was administered. At 5 years and 7 months post-treatment, the patient remains recurrence-free with preserved function and appearance. This case highlights the therapeutic potential of multidisciplinary, non-surgical strategies for head and neck STS when histologic ambiguity exists and radical surgery poses significant risk.