title: Sacral pneumatocysts: CT appearance.
abstract: OBJECTIVE
  CT findings of pneumatocyst of the sacrum have been evaluated.
  
  
  METHODS
  Eight patients, six men and two women, with pneumatocysts of the sacrum were studied. Selective CT with 4 and 2 mm thickness was performed, and the intralesional attenuation coefficients were measured.
  
  
  RESULTS
  All patients showed subchondral pneumatocysts of the sacrum with sclerotic margins related to the synovial portion of the sacroiliac joint. Intraarticular gas was found in six cases, and evidence of communication between the lesion and the joint was observed in two patients. Signs of bone degeneration were present in all cases.
  
  
  CONCLUSIONS
  Pneumatocyst of the sacrum is a benign bone lesion associated with arthritic changes.
authors.affiliation: Department of Radiology, Hospital Clinic i Provincial de Barcelona, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Berenguer
authors.forename: J
authors.initials: J
authors.lastname: Pomés
authors.forename: N
authors.initials: N
authors.lastname: Bargalló
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001845:Bone Cysts / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012447:Sacrum / Q000000981:diagnostic imaging*; D013122:Spinal Diseases / Q000000981:diagnostic imaging; D014057:Tomography, X-Ray Computed