title: Giant cell bone lesions in the craniofacial region: a diagnostic and therapeutic challenge.
abstract: BACKGROUND
  Giant cell tumors of bone (GCTs) are common in the long bones, but rare in the craniofacial region, with only 1% of cases occurring in the latter. Clinical, radiological, and anatomical diagnosis of this locally aggressive disease, which occurs in response to trauma or neoplastic transformation, poses a major challenge in clinical practice.
  
  
  METHODS
  The present study describes a series of 4 cases and highlights the main features of the differential diagnosis and treatment of these lesions: GCT, giant cell reparative granuloma (GCRG), and the brown tumor of hyperparathyroidism.
  
  
  RESULTS
  GCT presents as a benign neoplasm, most typically affecting the knees, and rarely in the temporal and sphenoid bones. It is radiologically indistinguishable from GCRG due to its lytic, poorly defined appearance. The distinction can only be made microscopically, as the presence of multinucleated giant cells scattered throughout the stroma and the absence of a history of trauma favor a diagnosis of GCT. The brown tumor of hyperparathyroidism occurs with rapid, localized osteoclast activity secondary to the effects of increased parathyroid hormone (PTH) levels; parathyroid examination is indispensable.
  
  
  CONCLUSIONS
  The diagnosis and treatment of these lesions poses a major challenge due to their similar clinical presentation and radiological appearance. Accurate diagnosis is essential for definition of appropriate management, as complete resection is the goal in GCT and GCRG to avoid recurrence, whereas the brown tumor often yields to treatment of the underlying hyperparathyroidism.
authors.affiliation: University of São Paulo Medical School, Clinics Hospital USP, São Paulo, Brazil. bbarros20@hotmail.com
authors.forename: Bruno Barros Pinto
authors.initials: BB
authors.lastname: Borges
authors.forename: Marco Aurélio
authors.initials: MA
authors.lastname: Fornazieri
authors.forename: Ana Paula Correia de Araújo
authors.initials: AP
authors.lastname: Bezerra
authors.forename: Leandro Aurélio Liporoni
authors.initials: LA
authors.lastname: Martins
authors.forename: Fábio de Rezende
authors.initials: Fde R
authors.lastname: Pinna
authors.forename: Richard Louis
authors.initials: RL
authors.lastname: Voegels
mesh_terms: D000328:Adult; D000368:Aged; D002648:Child; D003937:Diagnosis, Differential; D005147:Facial Bones; D005260:Female; D018212:Giant Cell Tumor of Bone / Q000175:diagnosis* / Q000601:surgery; D006101:Granuloma, Giant Cell / Q000175:diagnosis* / Q000601:surgery; D006801:Humans; D008875:Middle Aged; D012888:Skull Neoplasms / Q000175:diagnosis* / Q000601:surgery