OrthoNet

Rare Forms of Osteosarcoma:

Telangiectatic Osteosarcoma:
- 50 yrs)
- prognosis worse than 1o osteosarcoma

Parosteal Osteosarcoma:
- arises from external surface of bone
- usu in 3rd decade of life involving posterior aspect of distal femur
- presents as painless mass behind the knee
- low-grade malignancy - osteoid & woven trabeculae separated by intervening fibroblasic stroma with minimal cytologic atypia
- wide resection has good local control (80% 5 yr survival) without chemo or radiation
Periosteal Osteosarcoma:
- most common on diaphysis of tibia & femur
- presents as a painful mass
- xrays - ill-defined diaphyseal surface lesion with variable matrix mineralization with a �scooped-out� appearance +/- sunburst reaction or Codman�s triangle
- usu no marrow involvement
- histologically, predominant cartilaginous component with neoplastic osteoid production; lobulated with peripheral condensations of spindle cells
- wide resection with neoadjuvant chemotherapy