Imaging features of synovial chondromatosis of the spine: a review of 28 cases.

OBJECTIVE: To describe the radiographic, CT, and MRI appearance of synovial chondromatosis of the spine.

MATERIALS AND METHODS: Radiology and pathology databases were searched for cases of spinal synovial chondromatosis from 1984 through 2013, yielding 29 patients (16 males, 13 females). The average age was 45 years. Twenty-eight patients had imaging studies available for review including seven radiographs, two myelograms, 13 CT, and 23 MRI exams.

RESULTS: Cases were located in the cervical spine (16), thoracic spine (6), lumbar spine (6), and sacrum (1). Twenty-two cases (79%) had an epidural component. Eighteen (64%) had a neural foraminal component. Sixteen (57%) had a paraspinal component. The mass abutted a facet joint in 96% of cases. Nearly all (96%) showed a normal facet joint without internal erosive changes. Most (79%) showed evidence of chronic extrinsic bony erosion, usually involving the surface of the facet. Only 44% had calcifications as a dominant finding. Most patients (88%) had evidence of neural compression. On T1-weighted MRI, 80% showed intermediate or a combination of intermediate and dark signal. On T2-weighted images, 89% showed heterogeneous signal with discrete areas of dark signal. The majority (83%) showed a peripheral pattern of enhancement, usually peripheral nodular.

CONCLUSIONS: Synovial chondromatosis should be considered in the differential diagnosis when evaluating an epidural and/or paraspinal mass near a facet joint, especially when there is evidence of chronic extrinsic bone erosion, dark signal or nodules on T1 and/or T2, and nonenhancing fluid or myxoid signal centrally with thin or nodular peripheral enhancement.