Reconstruction of C-1 lateral mass with titanium mesh cage after resection of an aneurysmal bone cyst of the atlas.

Aneurysmal bone cysts (ABCs) are rare benign tumors with a prevalence of 0.14 cases per 100,000 people. A majority of cases arise during adolescence, and there is a female predominance. This lesion accounts for 1.4% of all primary bone tumors. Aneurysmal bone cysts occur mainly in the long bones, with spinal involvement in 10-30% of cases. Cervical spine ABCs account for about one-third of spinal ABCs, and atlas involvement occurs in 1% of cases. Resection of ABCs at the atlas is difficult because of the location and the lack of proper instrumentation for reconstruction of C-1. The authors present a case of an ABC at C-1 in a child who underwent resection of the lesion and reconstruction of the lateral mass with a titanium mesh cage.