• Definition: a rare, very aggressive vascular malignancy, arising from endothelial cells of blood or lymphatic vessels
• Epidemiology: peak incidence age > 70 years
• Etiology
  • Radiation (e.g., radiation therapy)
  • Chronic lymphedema: especially in postmastectomy lymph node resection
    • Likely due to a combination of increased lymphatic proliferation, which increases the likelihood of malignant cells, and a decreased number of lymph nodes, which decreases the ability to remove the malignant cells.
  • Chemicals: Vinyl chloride and arsenic are implicated in hepatic angiosarcoma.
• Clinical features
  • Location
    • More common in sun-exposed areas
    • Usually occur on the head, neck, and breast
    • May involve the internal organs (e.g., hepatic angiosarcoma)
  • Lesion
    • Blue/purple-colored with a bruise-like appearance
    • Later stage: hemorrhage or ulceration
    • High variability in appearance