title: Parosteal osteoliposarcoma: a new bone tumor (from imaging to immunophenotype).
abstract: BACKGROUND
  Parosteal osteosarcomas and well-differentiated liposarcomas (WDLPS) of soft tissue share several features: they are slowly progressive, locally aggressive tumors, tend to recur locally, and rarely or never metastasizes if not dedifferentiated. Their treatment is wide surgical resection. Microscopically, both are well differentiated tumors, very like their normal tissue counterpart. They share simple karyotypes with supernumerary ring chromosomes or giant marker chromosomes containing amplified 12q sequences including MDM2 and CDK4 genes, with subsequent overexpression of MDM2 and CDK4 proteins. We present the case of a parosteal osteoliposarcoma made of closely intermingled components of a low-grade osteosarcoma and a WDLPS.
  
  
  METHODS
  In a 34 year-old woman with a slowly growing mass of the arm, imaging revealed a large well-defined heterogeneous parosteal mass of the upper humerus, with two main components: bone at the base and fat at the periphery. Microscopically, these two components were consistent respectively with low grade osteosarcoma and WDLPS. Cells of the two components were labeled with anti-CDK4 antibody. No labeling with anti-MDM2 antibody and no signal detected with MDM2 FISH analysis were likely due overdecalcification. No frozen tumor tissue was available for FISH analysis nor array-CGH.
  
  
  CONCLUSIONS
  Differential diagnoses of this new entity would be a well-differentiated liposarcoma with a low-grade osteosarcomatous component that originates from the soft tissues, ruled out on imaging, and an ossifying parosteal lipoma, ruled out on immunohistochemistry.
  
  
  CONCLUSIONS
  This is the first description of a low-grade parosteal sarcoma with two components that morphologically and immunophenotypically demonstrate characteristics of a parosteal osteosarcoma and of a well-differentiated liposarcoma.
authors.affiliation: Université Paris Descartes, Sorbonne Paris Cité, Paris, France; Department of Pathology, Rizzoli Institute, Bologna, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Larousserie
authors.forename: X
authors.initials: X
authors.lastname: Chen
authors.forename: Y
authors.initials: Y
authors.lastname: Ding
authors.forename: J
authors.initials: J
authors.lastname: Kreshak
authors.forename: S
authors.initials: S
authors.lastname: Cocchi
authors.forename: Xiaoyuan
authors.initials: X
authors.lastname: Huang
authors.forename: Xiaohui
authors.initials: X
authors.lastname: Niu
authors.forename: M
authors.initials: M
authors.lastname: Alberghini
authors.forename: D
authors.initials: D
authors.lastname: Vanel
mesh_terms: D000328:Adult; D014408:Biomarkers, Tumor / Q000276:immunology*; D016207:Cytokines / Q000276:immunology; D005260:Female; D006801:Humans; D016130:Immunophenotyping; D008080:Liposarcoma / Q000145:classification / Q000175:diagnosis* / Q000276:immunology*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D012983:Soft Tissue Neoplasms / Q000145:classification / Q000175:diagnosis* / Q000276:immunology*; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D014408:Biomarkers, Tumor; D016207:Cytokines