Osteosarcoma

-Is a primary malignant tumor of bone; it is derived from undifferentiated connective tissue and forms neoplastic osteoid

1. How common is Osteosarcoma? Age group?

   1. It is the second most common primary malignant bone tumor, representing 20% of all primary malignant bone tumors.

   2. It is 2x more common than chondrosarcoma, 3x more frequent than Ewings sarcoma.

   3. 75% of cases occur in the 10-25 year age range, with 2:1 male predominance.

2. Key clinical features.

   1. Painful swelling of the involved limb is a common presenting symptom

   2. The metaphyses of the distal femur, proximal tibia, and proximal humerus are the most common sites.

   3. Only 3.5-7% occur in the spine

3. Key radiologic features

   1. The classic lesion presents as a permeative or ivory medullary lesion in the metaphysis of a long tubular bone with a poorly defined zone of transition.

   2. A sunburst or sunray periosteal response is characteristic

      1. Sunburst= periosteal reaction that often takes place within an extracortical, dense soft tissue mass that displays transverse spicules or radiating striations.

   3. Often, Codman’s triangle is found associated with the destructive lesions

      1. This is a reactive response to the lifting of the periosteum and is not pathognomonic for osteosarcoma b/c it may also be found in benign conditions such as traumatic periostitis, osteomyelitis, eosinophilic granuloma, and thyroid acropachy.

   4. Cortical disruption with soft tissue mass formation, often growing to large dimensions, occurs. The peripheral edge of an eccentric lobulated mass whose margins are roughened and irregular may be referred to as the cumulus cloud appearance.

4. Prognosis

   1. A 20% 5-year survival rate has been traditional; studies using intensive chemotherapy report 80% survival rate

   2. Amputation has offered the best tx when the lesion is surgically accessible.

Category: Orthopedics Notes , Tumors Revision