title: Retroperitoneal schwannomas in the anterior pararenal space: dynamic enhanced multi-slice CT and MR findings.
abstract: BACKGROUND
  To evaluate the imaging features of schwannomas in the anterior pararenal space (APS), especially focusing on dynamic enhanced multi-slice CT (MSCT) and MR findings.
  
  
  METHODS
  Eight patients with pathologically proved retroperitoneal schwannomas in the APS underwent dynamic enhanced multi-slice CT (MSCT), while three of these patients also had a contrast-enhanced MR examination. The imaging findings were retrospectively reviewed.
  
  
  RESULTS
  All eight cases exhibited forward displacement of the pancreas, and three cases showed lateral displacement and compression of the inferior vena cava. The tumors had round or oval shape with a maximal axial diameter of 4.0-12.3 cm (average, 6.7 cm). All eight tumors were solitary and well circumscribed. Of the eight retroperitoneal schwannomas in the APS, six exhibited a capsule with thickness of 1.0-2.0 mm, one showed punctate calcification, two displayed cystic degeneration, and three revealed a "target sign" on CT and MR. The tumors were hypo-dense on unenhanced CT images, hyper-intense on T2W images, and homogeneously hypo-intense on T1W images. All eight tumors exhibited gradual enhancement on dynamic enhanced CT or MR images. One case showed delayed enhancement. Heterogeneous enhancement was the dominant pattern occurring in seven out of eight tumors.
  
  
  CONCLUSIONS
  The imaging findings of schwannoma in the APS correspond with its pathological composition. Schwannoma should be included in the differential diagnosis of tumors in the APS.
authors.affiliation: Department of Radiology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, 107 Yan Jiang Xi Road, Guangzhou, 510120, Guangdong Province, China. liu.qingyu@163.com
authors.forename: Qing-Yu
authors.initials: QY
authors.lastname: Liu
authors.forename: Xiao-Feng
authors.initials: XF
authors.lastname: Lin
authors.forename: Wei-Dong
authors.initials: WD
authors.lastname: Zhang
authors.forename: Hai-Gang
authors.initials: HG
authors.lastname: Li
authors.forename: Ming
authors.initials: M
authors.lastname: Gao
mesh_terms: D000328:Adult; D003287:Contrast Media; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009442:Neurilemmoma / Q000175:diagnosis* / Q000000981:diagnostic imaging; D012186:Retroperitoneal Neoplasms / Q000175:diagnosis* / Q000000981:diagnostic imaging; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D003287:Contrast Media