Synovial chondromatosis of the temporomandibular joint is a rare condition, and only 10 cases with intracranial extension have been reported in the literature. Two cases of synovial chondromatosis with intracranial extension, followed up for 3 to 9 years, are reported here. The surgical treatment modality is described for each case.
Synovial chondromatosis is a rare condition in which there is cartilaginous metaplasia of the mesenchymal remnants of the synovial tissue of the joints. It is more of an active metaplastic process than a neoplastic one . Some aggressive lesions erode the underlying bone or joint capsule to invade the peri-articular area. The condition most commonly affects the knee, hip, elbow, wrist, ankle, and shoulder . Involvement of the temporomandibular joint (TMJ) in synovial chondromatosis is rare .
Synovial chondromatosis of the TMJ was first reported by Baron Albrecht von Haller in 1764. The first histological description was by Axhausen in 1933 .
When the cartilaginous mass invades the superior joint space in synovial chondromatosis of the TMJ, it erodes the cranial base of the middle cranial fossa region and infratemporal fossa involving the greater wing of the sphenoid. Only 10 cases of synovial chondromatosis eroding the middle cranial fossa have been reported to date .
A 43-year-old male presented with pain over the left pre-auricular region and restricted mouth opening of 2-year duration. Clinical examination showed diffuse swelling over the left TMJ, which was tender and firm on palpation. The mandible deviated on opening.
A computed tomography (CT) scan showed erosion of the glenoid fossa and articular tubercle, with intracranial extensions ( Fig. 1 ). No loose bodies were detected. A diagnosis of chondrosarcoma was considered.
The patient was operated in the presence of a neurosurgeon. An extended pre-auricular incision was made to expose the zygomatic arch and left TMJ. The glenoid fossa and pre- and post-glenoid tubercle were eroded with cartilaginous tissue. The meniscus was grossly involved. As the cartilaginous mass was resected along with the meniscus, the dura was easily separable. No intracranial involvement was seen. The tissue was sent for frozen section examination, which revealed chondroid tissue metaplasia with no sarcomatous changes. A temporalis myofascial flap was raised, rotated under the zygomatic arch to cover the defect, and secured with 4–0 Prolene sutures. Histopathology of a paraffin section led to the diagnosis of synovial chondromatosis.
The patient has been followed up for 9 years, with no signs of recurrence ( Fig. 2 ).
A 35-year-old male presented with pain over the right pre-auricular region of 6-year duration and gradual swelling with restricted mouth opening for 1 year. He had been treated conservatively with analgesics and heat therapy. Clinically, there was a firm and diffuse swelling over the right TMJ. Jaw movements were painful and limited, with deviation on opening.
CT and magnetic resonance imaging (MRI) showed an irregular mass with multiple radiopacities involving the right TMJ and eroding the greater wing of the sphenoid bone ( Figs 3 and 4 ). The diagnosis of synovial chondromatosis was considered.