Benign aggressive lesions cause more substantial bone destruction than active lesions and may also result in pathological fractures. This group of tumors includes giant cell tumor, aneurysmal bone cyst, osteoblastoma, chondroblastoma, and chondromyxoid fibroma. Depending on the extent of local bone destruction, eosiniophilic granuloma may be classified as either active or aggressive.
- The margin around these lesions may be geographic or ill-defined permeative.
- Small soft tissue masses may result from the lesion growing through the cortex, but the periphery of the lesion is often defined by a periosteal neo-cortical response.
- There is typically no risk of metastasis in these lesions, although a very small percentage of giant cell tumors may spread to the lungs.