title: Imaging features of synovial chondromatosis of the spine: a review of 28 cases.
abstract: OBJECTIVE
  To describe the radiographic, CT, and MRI appearance of synovial chondromatosis of the spine.
  
  
  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.
authors.affiliation: Department of Radiology, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA. littrell.laurel@mayo.edu.
authors.forename: Laurel A
authors.initials: LA
authors.lastname: Littrell
authors.affiliation: Department of Anatomic Pathology, Mayo Clinic, Rochester, MN, USA.
authors.forename: Carrie Y
authors.initials: CY
authors.lastname: Inwards
authors.affiliation: Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN, USA.
authors.forename: Franklin H
authors.initials: FH
authors.lastname: Sim
authors.affiliation: Department of Radiology, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA.
authors.forename: Doris E
authors.initials: DE
authors.lastname: Wenger
mesh_terms: D015838:Chondromatosis, Synovial / Q000000981:diagnostic imaging* / Q000473:pathology*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013122:Spinal Diseases / Q000000981:diagnostic imaging* / Q000473:pathology*; D014057:Tomography, X-Ray Computed / Q000379:methods; D021801:Zygapophyseal Joint / Q000000981:diagnostic imaging* / Q000473:pathology*
keywords: Epidural mass; Facet joint; Paraspinal mass; Sacrum; Spine; Synovial chondromatosis