UCLA Radiological Sciences Proceedings

An aneurysmal bone cyst (ABC) is a rare benign expansile lesion of the bone that consists of hemorrhagic cystic spaces separated by fibrous connective tissue containing osteoid and multinucleated giant cells. The lesion may be primary or secondary. We present a case of ABC in a 7-month-old girl who had a growing, antibiotic-refractory mass in the left chest wall. A computed tomography of the chest confirmed the anatomic location of the mass, but a percutaneous image-guided biopsy and video-assisted thoracoscopic surgery performed during work-up were nondiagnostic. The patient ultimately had a partial rib resection via left thoracotomy. On histologic examination, the mass was found to be an ABC. To our knowledge, this is the second case reported on aneurysmal bone cyst of the rib in an infant. The presented case confirms that ABCs can affect any bone and suggests that the inclusion of an expansile osteolytic lesion of the ribs in differential diagnosis is necessary to facilitate timely treatment that warrants excellent results.