Epidemiology
This is a low-grade cartilage lesion in the long and short bones of the limbs, mainly in adults. In the limbs it usually has a low risk of metastasis, but mechanical pain, deep scalloping, or growth call for close follow-up.
Basic features
It can be hard to distinguish from an active enchondroma; pain, growth, deep scalloping, or changes in the outer bone (cortex) raise the suspicion. The name “atypical cartilaginous tumor” is used only in the long and short bones of the limbs; an identical lesion in flat bones such as the pelvis or the scapula, or elsewhere in the axial skeleton, is called grade 1 chondrosarcoma and is usually treated more aggressively.
Usual treatment
The choice is between surveillance, extended curettage, or en-bloc resection depending on the site, symptoms, size, and how aggressive it looks on imaging. In the long bones of the limbs extended curettage is enough in most cases; resection is reserved for bulky or recurrent lesions, or those with cortical breach or a soft-tissue mass. In the pelvis and scapula, where the same lesion is called grade 1 chondrosarcoma, en-bloc resection is the preferred approach, because a recurrence is far harder to salvage.
Outcomes and prognosis
In the limbs the risk of metastasis is very low and the prognosis is favorable, but follow-up is needed because it can progress or recur locally.