title: Imaging characteristics of primary cranial Ewing sarcoma.
abstract: BACKGROUND
  Ewing sarcoma accounts for 10-15% of all childhood malignant bone tumours and is second in prevalence to osteosarcoma. The skull bones are an unusual site of origin of primary Ewing sarcoma in children. Previous reports concentrate on the neurosurgical aspects and relatively good outcome compared to other bone tumours of the calvarium. Reported cases mainly describe the imaging characteristics on CT.
  
  
  OBJECTIVE
  To describe the MRI and CT features of primary cranial Ewing sarcoma.
  
  
  METHODS
  The neuroimaging of three cases of primary cranial Ewing sarcoma are reviewed.
  
  
  RESULTS
  Our three cases show an extra-axial mass that is high attenuation on CT and low signal on T2-weighted MRI. Haemorrhagic components, dural extension and contrast enhancement are also characteristic features.
  
  
  CONCLUSIONS
  CT attenuation and magnetic resonance signal characteristics reflect sheets of densely packed cells seen in Ewing sarcoma.
authors.affiliation: Departments of Radiology, Great Ormond Street Hospital for Children, Great Ormond Street, London, WC1N 3JH, UK. wyli@btinternet.com
authors.forename: Wai-Yung
authors.initials: WY
authors.lastname: Li
authors.forename: Penelope
authors.initials: P
authors.lastname: Brock
authors.forename: Dawn E
authors.initials: DE
authors.lastname: Saunders
mesh_terms: D002648:Child; D002675:Child, Preschool; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D012512:Sarcoma, Ewing / Q000175:diagnosis* / Q000628:therapy; D012888:Skull Neoplasms / Q000175:diagnosis* / Q000628:therapy; D014057:Tomography, X-Ray Computed