title: Differentiation of primary chordoma, giant cell tumor and schwannoma of the sacrum by CT and MRI.
abstract: OBJECTIVE
  To evaluate criteria to differentiate sacral chordoma (SC), sacral giant cell tumor (SGCT) and giant sacral schwannoma (GSS) with CT and MRI.
  
  
  METHODS
  CT and MR images of 22 SCs, 19 SGCTs and 8 GSSs were reviewed. The clinical and imaging features of each tumor were analyzed.
  
  
  RESULTS
  The mean ages of SC, SGCT and GSS were 55.1 ± 10.7, 34.3 ± 10.7 and 42.4 ± 15.7 years old. SCs (77.3%) were predominantly located in the midline of lower sacrum, while most SGCTs (73.7%) and GSSs (87.5%) were eccentrically located in upper sacrum. There were significant differences in age, location, eccentricity, morphology of bone residues, intratumoral bleeding and septations. Multiple small cysts were mainly observed in SGCTs (73.7%) with large central cysts in GSSs (87.5%). SGCTs expanded mainly inside sacrum while SCs and GSSs often extended into pelvic cavity (P = 0.0022). Involvement of sacroiliac joints and muscles were also different. Ascending extension within sacral canal was only displayed in SCs. The preservation of intervertebral discs showed difference between large and small tumors (P = 0.0002), regardless of tumor type (P = 0.095). No significant difference was displayed in gender (P = 0.234) or tumor size (P = 0.0832) among three groups.
  
  
  CONCLUSIONS
  Age, epicenter of the lesion (midline vs. eccentric and upper vs. lower sacral vertebra), bone residues, cysts, bleeding, septation, expanding pattern, muscles and sacroiliac joint involvement can be criteria for diagnosis. Fluid-fluid level is specific for SGCTs and ascending extension within the sacral canal for SCs. The preservation of intervertebral discs is related to tumor size rather than tumor type.
authors.affiliation: Department of Radiology, Ruijin Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China. Electronic address: smjsh@hotmail.com.
authors.forename: Ming-Jue
authors.initials: MJ
authors.lastname: Si
authors.forename: Cheng-Sheng
authors.initials: CS
authors.lastname: Wang
authors.forename: Xiao-Yi
authors.initials: XY
authors.lastname: Ding
authors.forename: Fei
authors.initials: F
authors.lastname: Yuan
authors.forename: Lian-Jun
authors.initials: LJ
authors.lastname: Du
authors.forename: Yong
authors.initials: Y
authors.lastname: Lu
authors.forename: Wei-Bin
authors.initials: WB
authors.lastname: Zhang
mesh_terms: D000328:Adult; D002817:Chordoma / Q000473:pathology*; D003937:Diagnosis, Differential; D005260:Female; D018212:Giant Cell Tumor of Bone / Q000175:diagnosis*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009442:Neurilemmoma / Q000175:diagnosis*; D015203:Reproducibility of Results; D012447:Sacrum / Q000000981:diagnostic imaging / Q000473:pathology*; D012680:Sensitivity and Specificity; D013125:Spinal Neoplasms / Q000175:diagnosis*; D014057:Tomography, X-Ray Computed / Q000379:methods*
keywords: CT; Chordoma; Giant cell tumor; MRI; Sacrum; Schwannoma