Resection and 3D-printed prosthetic reconstruction of a giant aneurysmal bone cyst in the atlas: illustrative case.

backgroundAneurysmal bone cysts (ABCs) are aggressive, destructive bone tumors. Treatment of ABCs occurring in the upper cervical spine remains challenging due to their proximity to critical nerves and blood vessels. OBSERVATIONS: The authors report the case of a patient with a giant ABC in the atlas. Imaging data showed that there were changes in the left bone of the atlas, spinal canal stenosis and instability at the craniovertebral junction, and the vertebral artery passed through the lesion. The combined far-lateral, transoral, and posterior midline approach was adopted to completely resect the lesion. Meanwhile, a personalized atlas prosthesis was fabricated by means of 3D printing to reconstruct the craniovertebral stability. After the operation, the patient's symptoms disappeared and there was no neurological dysfunction. During the 3-year follow-up, the lesion did not recur and the prosthesis and internal fixation devices were in a good position. LESSONS: In this case of a giant ABC of atlas, the authors successfully achieved complete resection of atlas lateral mass lesions through a combined posterior-anterior-posterior approach and used a 3D-printed prosthesis to reconstruct craniocervical stability, providing a surgical paradigm for similar cases. https://thejns.org/doi/10.3171/CASE25164.