MSK: Agressive Lesions Flashcards
(49 cards)
What are the most common primary osseous malignancies?
- Myeloma/plasmacytoma (27%)
- Osteosarcoma (20%)
- Chondrosarcoma (20%)
What is the best sign that an osseous lesion is aggressive?
A wide zone of transition (you can’t trace the edges of the lesion with a pencil)
Note: This indicates that the lesion is too fast for the bone to be able to create a sclerotic border around it.
Arrow
Codman triangle, indicating a very aggressive lesion
Note: The lesion grew so fast it burst out of the cortex, leaving the Codman triangle pushed away.
Arrow
Codman triangle, indicating that this is a Pathologic fracture due to a very aggressive lesion
What are the major subtypes of osteosarcoma?
- Intramedullary (85%)
- Parosteal (4%)
- Periosteal (1%)
- Telangiectatic (rare)
Common etiologies for osteosarcoma
- Idiopathic (most common)
- Radiation therapy
- Pagets
- Infarctions
Osteosarcoma is more common in what pt population?
Young pts (10-20 years)
What are the most common locations for osteosarcoma?
- Femur (40%)
- Proximal tibia (15%)
What type of periosteal reactions are suspicious for osteosarcoma?
- Subburst
- Lamellated
- Codman triangle
- Reverse zoning phenomenon
What is the classic cause of occult pneumothorax?
Osteosarcoma metastasis to the lung
Think osteosarcoma
Note: Sunburst periosteal reaction in the femur.
Why is it important to image the entire bone that contains an osteosarcoma?
Skip metastases occur in 5% of cases (usually proximal to the primary tumor)
Note: A bone scan is usually done during staging also for this reason.
What imaging studies are usually performed during osteosarcoma staging?
- Bone scan (monoostotic vs polyostotic)
- Chest CT (to look for lung mets)
- MRI of the entire involved bone (to look for skip lesions and plan biopsy)
When does osteosarcoma recurrence usually occur?
Within 2 years of surgical resection
What is the most common location for osteosarcoma relapse?
Lung (80%)
Note: Bone relapse occurs less frequently (20%).
Why is a second biopsy usually done following Neoadjuvant chemotherapy for osteosarcoma?
To predict outcome
Note: 90% tumor death is a good prognostic feature.
What is the classic location for a parosteal osteosarcoma?
Posterior distal femur metaphysis
Think parosteal osteosarcoma
Note: Posterior distal femur metaphysis is a common location.
Reverse zoning phenomenon…
Think osteosarcoma
Note: This is when you have soft tissue calcification with a denser matrix in the center and less dense matrix peripherally (the opposite of myositis ossificans).
Are parosteal osteosarcomas usually lower or higher grade?
Low grade (typically the lowest grade of all the subtypes of osteosarcoma)
Arrows
String sign, suspicious for parosteal osteosarcoma
Note: The radiolucent string separates the bulky tumor from the cortex.
List the major subtypes of osteosarcoma from best prognosis to worst prognosis
What is the classic location for a periosteal osteosarcoma?
Medial distal femur diaphysis
Think periosteal osteosarcoma
Note: Broad-based cortically attached tumor with aggressive, lamellated/Codman’s triangle periosteal reaction and associated partially mineralized soft tissue mass.
