Osteoid osteoma of the lateral mass of C5. Should excision be combined with fusion?

A 10-year-old girl presented with a 1-year history of pain and stiffness in her neck associated with left shoulder and arm pain. This was found to be caused by an osteoid osteoma of the lateral mass of C5. Surgical excision of the tumour was performed through a posterior approach. Following surgery, the patient's pre-operative pain resolved. However, 3 months later she developed a recurrence of neck pain secondary to cervical instability. Further investigation revealed a grade II spondylolisthesis at the C5/6 level. A combined anterior and posterior fusion was performed and the patient's instability pain rapidly resolved. At her 18-months' follow-up a solid fusion was confirmed radiologically and the patient remained asymptomatic with no evidence of tumour recurrence. The purpose of this report is to highlight the difficulty in diagnosing this condition as well as to emphasise the surgical technique required. It would appear that excision of the lateral mass will result in instability. To prevent this, fusion of the spine should always be considered at the time of surgical excision of the tumour.