Primary Aneurysmal Bone Cyst of the Distal Tibia Crossing the Open Physis.

Crossing the barrier of an open physis by primary aneurysmal bone cyst is an exceptional phenomenon. We present a rare case of primary active aneurysmal bone cyst of the distal tibia in a 15-year-old boy in whom the lesion had crossed the open lateral distal tibia physis. The diagnosis was confirmed by radiographs, computed tomography, magnetic resonance imaging, and histopathologic findings. The lesion was successfully treated by extended curettage and allograft impaction. The patient was asymptomatic when last seen at 30 months.