Intramedullary Osteosarcoma

Question 1

What are the most common sites for intramedullary osteosarcoma?

Answer 1

Distal femur, proximal tibia, proximal humerus, pelvis

Question 2

What are the two most common sites of metastasis for intramedullary osteosarcoma?

Answer 2

1) Lung

2) bone

Question 3

What gene can predispose to osteosarcoma?

Answer 3

Retinablastoma (Rb)

Question 4

What are poor prognostic factors in intramedullary osteosarcoma?

Answer 4

1) advanced stage of disease (most important)
2) Chemo response (98% necrosis is good sign)
3) Tumor site and size
4) High alkaline phosphatase, high LDH

Question 5

Stage intramedullary osteosarcoma with skip lesions?

Answer 5

Enneking Stage III

Question 6

What are some imaging and histological characteristics of intramedullary osteosarcoma?

Answer 6

1) must MRI entire bone to look for skip lesions
2) CT chest to look for mets
3) Very hot on bone scan
4) Cellular atypia, lacey osteoid
5) Can be chondroblastic, osteoblastic, or fibroblastic

Question 7

What is the treatment for intramedullary osteosarcoma?

Answer 7

1) Pre-operative multi-agent chemo for 8-12 weeks (98% necrosis is good sign)
2) Limb salvage resection (low grade can do wide surgical resection)
3) Post-op chemo for 6-12 months