When Sarcoma Strikes the Jaw: A Rare Case of Intraosseous Synovial Sarcoma

Introduction Synovial sarcoma (SS) is a malignant soft tissue tumor of uncertain histogenesis which forms 5–10% of all soft tissue sarcomas and most commonly presents in the extremities. SS of the head and neck region forms 6–7% of all cases and most common site is the hypopharynx, parapharyngeal spaces and posterior pharyngeal wall. We report a rare case of primary synovial sarcoma arising from the mandibular bone treated with surgical resection and adjuvant radiotherapy. Case presentation A 52-year-old gentleman presented with a 6-month history of swelling in the left lower jaw associated with dull pain and loosening of teeth which, on examination, was revealed to be a 6 x 4 cm mass in the left mandibular region. CECT revealed an ill-defined heterogenous soft tissue lesion of 52 x 39 mm in the left lower mandible with destruction of the bone. Incisional biopsy showed plump spindly cells positive for CK, vimentin, Bcl2 and TLE-1 and negative for P63, P40, caldesmon, SMA, HMB45, S100 and beta-catenin confirming synovial sarcoma. The patient underwent wide local excision of the tumor with enbloc segmental mandibulectomy and supra-omohyoid neck dissection with fibular osteocutaneous free flap reconstruction. Due to the high-grade nature of SS, the tumor bed and neck was treated with adjuvant radiotherapy (50.4 Gy in 25 fractions). Conclusion Primary synovial sarcoma of the mandible is rare and carries poor prognosis. Histological confirmation is possible through immunohistochemistry and genetic testing. Surgical resection is the mainstay of treatment with radiotherapy reserved for aggressive cases