title: Macrophage-rich epithelioid angiosarcoma mimicking malignant melanoma.
abstract: BACKGROUND
  Cutaneous epithelioid angiosarcoma is a type of cutaneous angiosarcoma and usually arise both on the head or neck of the elderly.
  
  
  METHODS
  An 86-year-old male with an epithelioid angiosarcoma of the scalp that mimicked malignant melanoma.
  
  
  RESULTS
  A large irregular dark grey-blue plaque with an adjacent speckled tan nodule was suggestive of a primary cutaneous malignant melanoma with adjacent in-transit metastasis. Both had a well-circumscribed growth pattern and were composed of numerous large epithelioid cells with scattered severe atypia and mitoses. The tumor was positive for S-100 protein and vimentin and negative for low- and high-molecular weight cytokeratins. However, at high power, the epithelioid cells with severe atypia were negative for S-100 protein, and abundant large epithelioid macrophages were responsible for the S-100 protein positivity. The malignant tumor cells were negative for HMB-45, positive for CD31 and Factor VIII-related antigen, and focally positive for CD34. A focus of infiltrative, classical angiosarcoma with irregular vascular channels lined with plump, anaplastic endothelial cells was then found deep to the epithelioid tumor.
  
  
  CONCLUSIONS
  Macrophage-rich epithelioid angiosarcoma demonstrates abundant S-100 protein-positive epithelioid macrophages. This subset of epithelioid angiosarcoma may mimic malignant melanoma and may present as a pitfall in diagnosis.
authors.affiliation: Department of Dermatology, Boston University Medical School and Boston University Medical Center, Boston, MA 02118, USA.
authors.forename: Lori A
authors.initials: LA
authors.lastname: Brightman
authors.forename: Marie-France
authors.initials: MF
authors.lastname: Demierre
authors.forename: H Randolph
authors.initials: HR
authors.lastname: Byers
mesh_terms: D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000032:analysis; D001706:Biopsy; D003937:Diagnosis, Differential; D015622:Epithelioid Cells / Q000737:chemistry / Q000473:pathology*; D006394:Hemangiosarcoma / Q000737:chemistry / Q000473:pathology* / Q000601:surgery; D006801:Humans; D008264:Macrophages / Q000737:chemistry / Q000473:pathology*; D008297:Male; D008545:Melanoma / Q000473:pathology*; D009418:S100 Proteins / Q000032:analysis; D012535:Scalp; D012878:Skin Neoplasms / Q000737:chemistry / Q000473:pathology* / Q000601:surgery; D014746:Vimentin / Q000032:analysis
chemical_list: D014408:Biomarkers, Tumor; D009418:S100 Proteins; D014746:Vimentin