An unusual and difficult diagnosis of synovial chondromatosis: A case report

Synovial chondromatosis (SC) is a reactive joint disorder characterized by the development of metaplastic cartilaginous nodules floating within the joint space. We report a case of SC of the temporomandibular joint (TMJ) which had difficulty in diagnosis in a 40-year-old woman. The patient had TMJ pain with mandibular lateral deviation for two years. CT and MRI revealed well-defined and round-shaped bone resorption at the right mandibular fossa and an ovoid-shaped expansion of the superior articular cavity, which showed heterogeneous high signal intensity on T2-weighted MRI. Following a clinical diagnosis of benign TMJ tumor, the lesion was surgically removed. Histopathologically, it was diagnosed as SC in Milgram's stage 1, mainly involving the upper joint space. This is the first case report of SC in an early stage in which no cartilaginous nodules were generated but instead the mandibular fossa of the temporal bone was resorbed.