A 18 year old patient presents with right tibial pain and history of trauma in the vicinity of the symptoms.
Performed biopsy revealed chondroblastic osterosarcoma.
GENERAL FEATURES
Osteosacroma is the common malignant bone tumor accounting for 25% of all primary bone malignancies.
It is characterized by pleomorphic nature and depending on the cell line predominance, it is classified as:
· osteoblastic ® osteoblasts predominate
· chondroblastic ® composed of cells of cartilaginous origin
· fibroblastic
· telangiectasic
Affects mostly young people, 10-25 years of age with slight male preference.
Usual site of involvement - femoral metaphysis,
- proximal end of tibia,
- upper end of humerus
IMAGING
X-RAY FINDINGS
- Bone destruction, eccentrically located due to tumor invasion
- Cortical erosion and presence of well-defined soft tissue mass
- Periosteal elevation and disruption due to new bone formation (Godman’s triangles)
- Combined bone sclerosis and destruction
- Occasionally the lesion is purely lytic (chondroblastic, fibroblastic)
1) Combined sclerotic and osteolytic lesion with well defined soft tissue mass with calcifications, usually arranged in ring-like pattern.
2) Lytic medullary lesion
3) The bone appears slightly expanded
CT:
- highlights the x-ray findings
- detects the extent of tumor growth (endosteal or extraskeletal)
- nonspecific or pin-point or ring-like pattern calcifications are investigated better
- required for staging of the disease.
MRI:
- prominent heterogenous mass surrounded by bone mass and commonly soft tissue involvement,
- very low intensity signal characteristic for the calcified and sclerotic sites, on all image,
- the tumor mass itself present with high-intensity signal on T2-weighted images,
- IV contrast medium enhancement is observed significantly in the non-osteosclerotic areas,
- Examination of choice for localized staging of the disease which may reveal the so called “skip lesions” (metastases in the bone itself)
1) other bone malignancies
2) metastases
3) chronic bone infections
Further Reading
1. Kumar R., David R., Madewell J.E., Lindell Jr M.M. (1987)
Radiographic spectrum of osteogenic sarcoma. Am. J. Roentgenol., 148: 767-72.
2. David Sutton: Textbook of Radiology and Imaging. International Edition reprint 2000.