ANEURYSMAL BONE-CYST - RADIOLOGICAL FEATU RES IN 71 CASES

A multicenter study of 71 patients with aneurysmal bone cyst (ABC) sho wed that 85% of cases were characterized by typical radiological featu res consisting of a sharply marginated, expansile, eccentric lesion wi th a honeycomb structure that displaced the soft tissues without disru pting the cortex. Sites of involvement were the long tubular bones of the limbs (72%; femur, 30%; tibia, 18%, humerus, 11%), short bones (24 %), and flat bones (4%). The bone segments involved were the metaphysi s and diaphysis in 43% of cases, the epiphysis and metaphysis in 20%, the metaphysis in 18%, the diaphysis in 11%, and the epiphysis, metaph ysis, and diaphysis in 8%. Age was younger in patients with involvemen t of the metaphysis or metaphysis and diaphysis (12-13 years) than in those with involvement of the epiphysis, metaphysis, and diaphysis (20 -28 years). Some patients, especially those with secondary ABCs, had a typical features on plain radiographs suggestive of a malignant tumor. Computed tomography was helpful in demonstrating a low attenuation co efficient within the tumor that increased slightly after intravenous a dministration of a contrast agent. A fluid-fluid level was seen in one of the four patients who had computed tomography; this finding is hig hly suggestive of ABC, the only other lesion in which it has been repo rted being telangiectatic osteosarcoma. One patient was successfully t reated by arteriography with embolization, which induced minimal bleed ing. Magnetic resonance imaging was not used in this series.