Less common precursor lesions were fibrous dysplasia, non-ossifying fibroma, chondromyxoid fibroma, unicameral bone cyst, fibrous histiocytoma, eosinoplilic granuloma, and osteosarcoma. A translocation involving the 16q22 and 17p13 chromosomes has been identified in the solid variant and extraosseous forms of aneurysmal bone cyst. The clinical presentation of an ABC is swelling, tenderness and pain. Occasionally there is limited range of motion due to joint obstruction. Spinal lesions can cause neurological symptoms secondary to cord compression.
Pathological fractures are rare due to the eccentric location of the lesion.
Depending on the location, the differential includes UBC, chondromyxoid fibroma, giant cell tumor, osteoblastoma and the highly malignant telangiectatic osteosarcoma. On plain film, an ABC is normally placed eccentrically in the metaphysis and appears osteolytic. The periosteum is elevated and the cortex is eroded to a thin margin. CT scan can also help delineate lesions in the pelvis or spine where plain film imaging may be inadequate. CT scan can narrow the differential dignosis of ABC by demonstrating multiple fluid-fluid levels within the cystic spaces.