Synovial Chondromatosis of TMJ with Glenoid Dehiscence: Case Report

Abstract

Synovial chondromatosis is a rare benign entity characterized by cartilaginous metaplasia of the synovial membrane. Its location in the temporomandibular joint (TMJ) is uncommon and, in elderly patients, mandates ruling out synovial chondrosarcoma. A 71-year-old woman, with no relevant comorbidities, presented with two years of right preauricular pain, mandibular deviation, joint crepitus, and a maximum mouth opening of 30 mm. Computed tomography revealed multiple intra-articular hyperdense bodies involving both supradiscal and infradiscal compartments, with mild condylar erosive changes. An open preauricular approach was performed, identifying approximately 20 cartilaginous loose bodies and a dehiscence of the glenoid fossa roof toward the middle cranial fossa, prompting subtotal excision without formal synovectomy. Histopathological and immunohistochemical study (S-100+, IDH-1−, Ki-67 ≈1%) confirmed calcified synovial chondromatosis, Milgram stage III, ruling out chondrosarcoma. At eight-month follow-up, the patient remained asymptomatic, with a maximum mouth opening of 42 mm (30 mm preoperatively) and no signs of reactivation. Bicompartmental involvement and glenoid roof dehiscence are uncommon findings that conditioned the surgical approach. Immunohistochemistry was decisive for ruling out chondrosarcoma. Subtotal management, although not generalizable, was pertinent in this specific anatomical scenario.  This case highlights the importance of rigorous histopathological and immunohistochemical assessment and of modulating surgical management in the presence of complex anatomical findings in advanced synovial chondromatosis of the TMJ.