title: Paratesticular liposarcoma with smooth muscle differentiation mimicking angiomyolipoma.
abstract: OBJECTIVE
  To discuss the differential diagnosis of a case of well-differentiated liposarcoma which had areas resembling angiomyolipoma-a feature which, to our knowledge, has not been reported previously.
  
  
  RESULTS
  A tumour in the paratesticular region had apparently been present for 40 years, but had grown recently. A fat component containing lipoblasts was admixed with areas resembling angiomyolipoma, i.e. desmin positive, but HMB45-negative smooth muscle proliferation with atypia and thick-walled blood vessels devoid of elastin.
  
  
  CONCLUSIONS
  The diagnosis of liposarcoma, rather than angiomyolipoma with adipose atypia, in this case is based on the fact that smooth muscle differentiation is documented in liposarcoma, lack of HMB45 staining and recent clonality studies which suggest that the fat in angiomyolipoma is not neoplastic.
authors.affiliation: Department of Histopathology/Cytology; Urology, Peterborough District Hospital, Peterborough, UK. pcps@dial.pipex.com
authors.forename: C
authors.initials: C
authors.lastname: Womack
authors.forename: A G
authors.initials: AG
authors.lastname: Turner
authors.forename: C
authors.initials: C
authors.lastname: Fisher
mesh_terms: D018207:Angiomyolipoma / Q000175:diagnosis / Q000473:pathology* / Q000503:physiopathology; D003937:Diagnosis, Differential; D006801:Humans; D008080:Liposarcoma / Q000175:diagnosis / Q000473:pathology* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009130:Muscle, Smooth / Q000473:pathology; D013736:Testicular Neoplasms / Q000175:diagnosis / Q000473:pathology* / Q000503:physiopathology