title: MDM2-positive atypical lipomatous neoplasm/well-differentiated liposarcoma versus spindle cell lipoma of the orbit.
abstract: OBJECTIVE
  To distinguish, in a 36-year-old man, an atypical lipomatous neoplasm/well-differentiated liposarcoma from a spindle cell lipoma in a recurrent orbital tumor.
  
  
  METHODS
  Clinical, radiographic, and histopathologic evaluations coupled with immunohistochemical studies for CD34, factor XIII, bcl-2, S-100, muscle-specific actin, Ki-67, and MDM2.
  
  
  RESULTS
  MDM2 gene amplification was discovered in the CD34 tumor cells. An average Ki-67 proliferation index of 28% was ascertained for the original and recurrent lesions. These findings established the diagnosis of a well-differentiated liposarcoma with lipoma-like and spindle cell features and ruled out a spindle cell lipoma.
  
  
  CONCLUSIONS
  Well-differentiated liposarcoma is a slow growing, infiltrative, and nonmetastasizing neoplasm that is microscopically and diagnostically challenging. It can be reliably separated from a benign spindle cell or an atypical lipoma by using the markers MDM2 and Ki-67.
authors.affiliation: Cogan Ophthalmic Pathology Laboratory, Massachusetts Eye & Ear Infirmary, Boston, Massachusetts 02114, USA. fred_jakobiec@meei.harvard.edu
authors.forename: Frederick A
authors.initials: FA
authors.lastname: Jakobiec
authors.forename: John
authors.initials: J
authors.lastname: Nguyen
authors.forename: Pooja
authors.initials: P
authors.lastname: Bhat
authors.forename: Aaron
authors.initials: A
authors.lastname: Fay
mesh_terms: D000199:Actins / Q000032:analysis; D000328:Adult; D018952:Antigens, CD34 / Q000032:analysis; D014408:Biomarkers, Tumor / Q000032:analysis*; D005176:Factor XIII / Q000032:analysis; D006801:Humans; D019394:Ki-67 Antigen / Q000032:analysis; D008067:Lipoma / Q000737:chemistry / Q000175:diagnosis* / Q000000981:diagnostic imaging; D008080:Liposarcoma / Q000737:chemistry / Q000175:diagnosis* / Q000000981:diagnostic imaging; D008279:Magnetic Resonance Imaging; D008297:Male; D009918:Orbital Neoplasms / Q000737:chemistry / Q000175:diagnosis* / Q000000981:diagnostic imaging; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000032:analysis; D051736:Proto-Oncogene Proteins c-mdm2 / Q000032:analysis*; D009418:S100 Proteins / Q000032:analysis; D014057:Tomography, X-Ray Computed
chemical_list: D000199:Actins; D018952:Antigens, CD34; D014408:Biomarkers, Tumor; D019394:Ki-67 Antigen; D019253:Proto-Oncogene Proteins c-bcl-2; D009418:S100 Proteins; D005176:Factor XIII; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2