Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
On x-ray, osteosarcoma is characterized by medullary and cortical bone destruction, periosteal reaction, tumor matrix calcification and soft tissue mass.[1]
X Ray
Conventional radiography continues to play an important role in diagnosis of osteosarcoma. Typical appearances of conventional high grade osteosarcoma include:[1]
- Medullary and cortical bone destruction.
- Wide zone of transition, permeative or moth-eaten appearance.
- Aggressive periosteal reaction characterized by:
- Sunburst appearance
- Codman triangle
- Lamellated (onion skin) reaction: less frequently seen
- Variable: reflects a combination of the amount of tumor bone production, calcified matrix, and osteoid.
- Ill-defined fluffy or cloud-like cf. to the rings and arcs of chondroid lesions.
Images courtesy of RadsWiki
- The following table illustrates the findings on x-ray for the subtypes of osteosarcoma:[1]
|
|
| Subtype
|
X-Ray findings
|
|---|
- Intracortical osteosarcoma
|
- Presents as an oval intracortical geographic osteolytic lesion in the diaphysis with surrounding sclerosis.
- Measures approximately 4 cm in length.
- Multiple calcific foci can be seen within the lytic region, suggesting osteoid matrix.
|
- Parosteal osteosarcoma
|
- Large lobulated exophytic, 'cauliflower-like' mass with central dense ossification adjacent to the bone.
- String sign: Thin radiolucent line separating the tumor from cortex, observed in 30% of cases.
- Tumor stalk: Grows within tumor in late stages and obliterates the radiolucent cleavage plane.
- +/- soft tissue mass.
- Cortical thickening without aggressive periosteal reaction is often seen.
- Tumor extension into medullary cavity is frequently observed.
|
- Periosteal osteosarcoma
|
- Typically seen as a broad-based surface soft-tissue mass causing extrinsic erosion of thickened underlying diaphyseal cortex and perpendicular periosteal reaction extending into the soft-tissue component.
|
- Telangiectatic osteosarcoma
|
- Typically seen as an expansile lytic metaphyseal bony lesion.
- Geographic bony destruction with wide zone of transition tends to be more common than permeative bony destruction.
- Less osteoid matrix compared from conventional type.
|
- Low grade osteosarcoma
|
- Because the fibrous dysplasia and central low-grade osteosarcoma are so similar histologically, the radiographic features are an extremely important part of the diagnosis.
- Radiographic features of low grade osteosarcomas are variable.
- Most common pattern is as a large intracompartmental expansile lytic fibro-osseous lesion with coarsely thick or thin incomplete trabeculations. Another less common pattern is as a dense sclerotic lesion.
- Cortical erosion and soft tissue extension is also a common feature.
|
- Extra skeletal osteosarcoma
|
- Soft tissue density with variable amount of calcification which represents osteoid matrix formation, and is seen in approximately 50% of cases.
|
References
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