Tumor biology
- Rare, slow-growing, benign, generally active cartilage lesion
- Not known to metastasize
- Arises on the surface of bone with underlying cortical scalloping
Age
Second through fourth decades
Gender
M:F = 1:1
Presentation
- Pain, tenderness at site of lesion
- Often accompanied by swelling
Physical findings
Localized swelling may be present
Plain films
Site
- Lesion eccentric, subperiosteal in location, external to cortex
- Medullary canal not involved
- Most common site: metaphyseal cortex of long bones (especially proximal humerus and femur), small tubular bones of hands and feet
Size
Variable
Tumor effect on bone
- Periosteal-based soft tissue lesion
- Typically causes erosion/scalloping.
Bone response to tumor
- Lesion is well defined, shallow, geographic
- Sharp sclerotic interface with underlying eroded cortical margin
- Peripheral periosteal elevation and reaction may be seen
Matrix
- Scattered calcifications may be present
- Lesions may be highly calcified and radiopaque
Cortex
Cortical scalloping/erosion by the overlying juxtacortical mass
Soft tissue mass
Always present
Differential diagnosis
- Periosteal chondrosarcoma
- Periosteal osteosarcoma
- Soft tissue neoplasm eroding adjacent cortical bone
Pathology
- Gross: Cartilage nodules located on surface of cortex
- Microscopic: Hyaline cartilage showing variable cellularity
- Cytological atypia may be present; correlation with radiologic appearance critical
- New bone formation may be present at interface of lesion and underlying cortical bone
Diagnosis and treatment
- Treatment of choice: en bloc resection with an intact narrow rim of normal bone
- Curettage has relatively high risk of recurrence
- Spilling cartilage into soft tissues by curettage increases risk of local relapse