Primary aneurysmal bone cyst of the distal tibial epiphysis: a case report.

Aneurysmal bone cyst (ABC) is a benign lesion that commonly involves the metaphysis or metadiaphyseal region of long bones in children. The WHO defined ABC as an expansile osteolytic lesion consisting of blood-filled spaces and channels that are divided by connective tissue septa that may contain osteoid tissue and osteoclast-like giant cells. ABCs are usually treated with intralesional procedures, and variables including surgeon technique, young patient, juxtaphyseal tumors, and tumor location have been associated with recurrence. Juxtaphyseal lesions breaching the physis have been described. There is only one case of primary ABC of the epiphysis in the literature. We present a second case in a 13-year-old boy who presented with a primary ABC of the distal tibial epiphysis, including diagnostic evaluation and treatment.