title: Expression of receptor activator of NF-κB ligand and osteoprotegerin in peripheral giant cell granulomas of the jaws.
abstract: BACKGROUND
  Peripheral giant cell granuloma is a tumor of the jaw characterized by the presence of multinucleated giant cells and mononuclear cells within a fibrous stroma. These lesions are considered to be of a reactive nature rather than neoplastic. Although peripheral giant cell granulomas is a well-described clinical entity, little is known on its pathogenesis. The aim of this study was to investigate the receptor activator of NF-κB ligand (RANKL) and osteoprotegerin (OPG) expression and immunolocalization in giant cell granulomas.
  
  
  METHODS
  RANKL and OPG protein expression was evaluated in 22 peripheral giant cell granulomas samples, by means of immunohistochemistry. Staining was evaluated semi-quantitatively, according to the extent and intensity of the stain.
  
  
  RESULTS
  RANKL was expressed in all cases with a cytoplasmic staining pattern, whereas OPG expression was detected in 21 of the 22 cases examined. Active multinucleated giant cells exhibited intense immunoreactivity for both proteins.
  
  
  CONCLUSIONS
  RANKL and OPG are expressed in peripheral giant cell granulomas of the jaw in a manner supporting the osteoclastic nature of giant cells whereas the possible osteoclastic lineage of stromal monocytes remains ambiguous.
authors.affiliation: First Department of Pathology, Medical School, National and Kapodistrian University of Athens, 75 M. Asias Street, GR 11527, Athens, Greece. gfanourak@med.uoa.gr
authors.forename: Galinos
authors.initials: G
authors.lastname: Fanourakis
authors.forename: Andreas C
authors.initials: AC
authors.lastname: Lazaris
authors.forename: Stylianos
authors.initials: S
authors.lastname: Krithinakis
authors.forename: Konstantinos I
authors.initials: KI
authors.lastname: Tosios
authors.forename: Alexandra
authors.initials: A
authors.lastname: Sklavounou
authors.forename: Sofia
authors.initials: S
authors.lastname: Tseleni-Balafouta
mesh_terms: D019070:Cell Lineage; D005347:Fibroblasts / Q000378:metabolism; D006101:Granuloma, Giant Cell / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D007571:Jaw Diseases / Q000378:metabolism*; D010010:Osteoclasts / Q000378:metabolism; D053244:Osteoprotegerin / Q000096:biosynthesis*; D053245:RANK Ligand / Q000096:biosynthesis*; D017154:Stromal Cells / Q000378:metabolism
chemical_list: D053244:Osteoprotegerin; D053245:RANK Ligand