Synovial chondromatosis presenting as an epidural mass.

Background: Synovial chondromatosis is an uncommon disorder characterized by the formation of multiple cartilaginous nodules in the synovium of the facet joint. It most commonly affects large joints such as hip or shoulder. Commonly seen features are bony erosion and calcifications. Synovial chondromatosis is rare in the spine and there are few previous reports of extension into the spinal canal.
Case Description: A 58-year-old man presented with a 2 year history of progressive numbness in the right upper extremity without objective weakness. A several month course of conservative management, including physical therapy, failed to alleviate symptoms. Magnetic resonance imaging of the cervical spine demonstrated the erosion of the right facet C5-C6 joint with listhesis and foraminal enlargement secondary to a lesion. Treatment was offered to the patient in the form of surgical resection. The lesion was removed in piecemeal fashion using curettes and Cavitron ultrasonic surgical aspirator. Histological examination demonstrated atypical well-differentiated cartilaginous proliferation.
Conclusion: This patient had an uncomplicated postoperative course and experienced complete resolution of right upper extremity sensory symptoms. Synovial chondromatosis may compromise cervical spinal cord and nerve roots if it extends into the spinal canal. Although it remains rare, it should be included in the differential diagnosis for upper extremity radiculopathy and myelopathy. Surgical resection is a viable treatment option for symptomatic patients with this pathology. In some cases, adequate resection may necessitate stabilization with instrumentation.