Distinguishing between enchondromas and low-grade conventional chondrosarcomas is often difficult due to both imaging and histological similarity.
Differentiating between them may be a moot point since both can be monitored clinically and radiologically. Pain has been regarded as an indication for surgery, however it is often impossible to be certain that the chondroid lesion is the source of pain.
Radiographic features
Useful features include:
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size
lesion size over 5-6 cm favors chondrosarcoma, however size alone may not be an indicator of malignancy 8
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cortical breach
seen in 88% of long-bone chondrosarcomas
seen in only 8% of enchondromas
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deep endosteal scalloping involving >2/3 of cortical thickness
seen in 90% of chondrosarcomas
seen in only 10% of enchondromas
bone and soft tissue edema can be seen in enchondroma and low-grade chondrosarcoma, more frequently in the latter 9
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permeative or moth-eaten bone appearance
seen in high-grade chondrosarcomas, not in low-grade tumors
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soft tissue mass beyond bone
not seen in enchondroma
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increased uptake on bone scan
seen in 82% of chondrosarcomas
seen in only 21% of enchondromas
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location
hands and feet are uncommon locations for chondrosarcoma
outside hand and feet, chondrosarcomas outnumber enchondromas 5:1
spine, pelvis, sacrum, and ribs are rare locations for enchondromas
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patient age
enchondromas commonly appear in young adults
chondrosarcomas tend to appear in middle-aged patients
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pain
chondrosarcomas almost always present with pain however it can be difficult or impossible to be certain that the tumor is actually the source of pain
enchondromas are painless unless they cause a pathological fracture