title: A case of giant cell reparative granuloma of the petrous bone: demonstration of the proliferative component.
abstract: BACKGROUND
  Giant cell reparative granuloma (GCRG) is an uncommon benign lesion of the bone. It typically arises in the mandible and rarely involves the skull. The cytologic nature and genesis of the involved cells are poorly understood.
  
  
  RESULTS
  We report a case of GCRG in the petrous bone of a 3-year-old girl. One year following gross total removal, the granuloma recurred locally and was resected en bloc at the second surgery. Histologically, the lesion was composed of oval or spindle-shaped stroma cells admixed with a number of multinucleated giant cells. Immunohistochemical study demonstrated that 5.6% of the stroma cells, but none of the multinucleated giant cells, were positive for MIB-1 antibody.
  
  
  CONCLUSIONS
  These results suggest that this lesion expands by proliferation of the stromal component, with a growth rate roughly between those of the typical benign and malignant brain tumors. The cytologic nature of the cells comprising this uncommon disease remains to be elucidated.
authors.affiliation: Department of Neurosurgery, Osaka University Medical School, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Maruno
authors.forename: T
authors.initials: T
authors.lastname: Yoshimine
authors.forename: T
authors.initials: T
authors.lastname: Kubo
authors.forename: T
authors.initials: T
authors.lastname: Hayakawa
mesh_terms: D002675:Child, Preschool; D005260:Female; D006101:Granuloma, Giant Cell / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery; D006801:Humans; D007150:Immunohistochemistry; D008279:Magnetic Resonance Imaging; D010579:Petrous Bone / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery; D012086:Reoperation; D014057:Tomography, X-Ray Computed