+ Biologic Behavior

  • HSA is a malignant neoplasm that arises from the endothelial cells
  • HSA account for 4% of all primary bone tumors
  • HSA should be differentiated from telangiectatic OSA
  • breed predisposition: GSD ± Boxers and Great Danes
  • sex predisposition: males
  • 43% HSA occur in the appendicular skeleton and 57% in the axial skeleton
  • sites: proximal humerus (most common), femur, ribs, vertebrae and scapula
  • multiple lesions are relatively common
  • soft tissue mass accompanies bony lesion in 50% of cases
  • pathologic fracture is common
  • = > 88% metastatic rate with metastatic disease developing < 6 months
  • metastatic sites include lungs, liver, spleen, heart, skeletal muscle, kidney, brain, and other long bones

+ Treatment

  • Survey radiographs: osteolytic with intramedullary extension and minimal cortical or periosteal changes
  • Ultrasonographic examination of the heart and abdominal cavity is recommended for primary lesions
  • Pulmonary metastatic disease is difficult to confirm as diffuse interstitial pattern mimics old age changes
  • 12-month survival rate < 10% even with single bone lesions