title: [Pathologic diagnosis of primary small round cell tumors of the bone].
abstract: OBJECTIVE
  To study the diagnosis and differentiation of primary small round cell tumors of bone.
  
  
  METHODS
  Thirty-nine cases were studied by light microscopy and immunochemistry of O13, NSE, S-100, Actin and LCA.
  
  
  RESULTS
  20/22 cases of EW/PNET were positive for O13.16/22 cases of EW/PNET and one case of small cell osteosarcoma were positive for NSE. S-100 was positive in EW/PNET, small cell osteosarcoma and mesenchymal chondrosarcoma. All malignant lymphomas were positive for LCA. 6 cases of small cell osteosarcoma have osteoid production. Islands of cartilage were found in mesenchymal chondrosarcoma.
  
  
  CONCLUSIONS
  O13 is a specific valuable marker for the diagnosis of EW/PNET. Histologic features of the osteoid in osteosarcoma and the cartilage in mesenchymal chondrosarcoma are important for the diagnosis.
authors.affiliation: Department of Pathology, Peking University First Hospital, Beijing 100034, China. jna4495@hotmail.com
authors.forename: Jia
authors.initials: J
authors.lastname: Na
authors.forename: Wanzhong
authors.initials: W
authors.lastname: Zou
authors.forename: Zhiwei
authors.initials: Z
authors.lastname: Fang
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhang
mesh_terms: D000293:Adolescent; D000328:Adult; D000951:Antigens, Neoplasm / Q000032:analysis; D001859:Bone Neoplasms / Q000737:chemistry / Q000473:pathology*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D007223:Infant; D008228:Lymphoma, Non-Hodgkin / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D018242:Neuroectodermal Tumors, Primitive / Q000473:pathology*; D010751:Phosphopyruvate Hydratase / Q000032:analysis; D012512:Sarcoma, Ewing / Q000473:pathology*
chemical_list: D000951:Antigens, Neoplasm; C062335:HBA-71 tumor antigen; D010751:Phosphopyruvate Hydratase