Metachronous aneurysmal bone cyst in a 9-year-old boy: case report and review of the literature.

Aneurysmal bone cyst (ABC) is a locally aggressive, benign bone tumor that commonly affects children. Metachronous ABCs are rare, and have been described only three times in the literature. Here we present a fourth case in a 9-year-old boy who presented with an ABC of the scapula; 2½ years later he presented with a tibial ABC. We also review the literature and discuss the pathological and clinical characteristics of this lesion.