title: Role of immunohistochemical cyclo-oxygenase-2 (COX-2) and osteocalcin in differentiating between osteoblastomas and osteosarcomas.
abstract: OBJECTIVE
  Differential diagnosis between aggressive osteoblastoma and low grade osteosarcoma may be very difficult or even impossible on a small biopsy. This study was designed to assess the usefulness of immunoexpression of COX-2 and osteocalcin in the differential diagnosis of the two tumour types.
  
  
  METHODS
  Immunostaining of COX 2 and osteocalcin were studied in 9 osteoblastomas and 30 osteosarcomas.
  
  
  RESULTS
  All osteoblastomas and 11/20 (55%) high-grade osteosarcomas showed COX-2 immunoreactivity. All low grade osteosarcomas were COX-2 negative. COX-2 was significantly higher (p<0.002) in osteoblastomas 9/9 (100%) than in osteosarcomas 13/30 (43%) and in aggressive osteoblastomas versus low grade osteosarcomas (p<0.01). Osteocalcin was found in tumour cells of all osteosarcomas and osteoblastomas and in the osteoid matrix of 84% of osteosarcomas and 78% of osteoblastomas. Strong osteocalcin was significantly higher (p<0.02) in osteoblastomas (78%) than in osteosarcomas (27%).
  
  
  CONCLUSIONS
  COX-2 is a valuable marker in distinction between osteosarcoma and osteoblastoma. Negative COX-2 could confirm the diagnosis of low grade osteosarcoma versus aggressive osteoblastoma. Intensity and distribution of osteocalcin may indicate the degree of osteoblastic differentiation.
authors.affiliation: Department of Pathology, Sohag University, Egypt.
authors.forename: Zeinab H
authors.initials: ZH
authors.lastname: El-Badawi
authors.forename: Eman M S
authors.initials: EM
authors.lastname: Muhammad
authors.forename: Hassan H
authors.initials: HH
authors.lastname: Noaman
mesh_terms: D000293:Adolescent; D000328:Adult; D014408:Biomarkers, Tumor / Q000378:metabolism; D001859:Bone Neoplasms / Q000175:diagnosis* / Q000378:metabolism / Q000601:surgery; D002452:Cell Count; D049109:Cell Proliferation; D002648:Child; D051546:Cyclooxygenase 2 / Q000378:metabolism*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques / Q000379:methods; D008297:Male; D008875:Middle Aged; D018215:Osteoblastoma / Q000175:diagnosis* / Q000378:metabolism / Q000601:surgery; D015675:Osteocalcin / Q000378:metabolism*; D012516:Osteosarcoma / Q000175:diagnosis* / Q000378:metabolism / Q000601:surgery; D055815:Young Adult
chemical_list: D014408:Biomarkers, Tumor; D015675:Osteocalcin; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human