Cervical Osteoid Osteoma Progression to Osteoblastoma.

A 16-year-old boy presented with 6 months of moderate neck pain, more severe at night, and temporarily relief by nonsteroidal anti-inflammatory drugs. Radiographs were normal. Magnetic resonance imaging showed edema in C6 vertebral body and surrounding C5–C6 posterior element. Computed tomography (CT) scan findings were consistent with osteoid osteoma located on the right pedicle of C6 (Fig. 2). Intralesional excision was proposed to the patient and parents who did not accept. One year later, the patient reported a worsening cervical pain no longer responsive to analgesics with root irritation in the right arm. A new CT scan showed considerable expansion of the lesion involving C6 right pedicle and articular process surrounding the C6 nerve root and vertebral artery, highly suspicious for osteoblastoma. An intralesional excision and posterior C4–C7 fusion provided immediate pain relief. Histologic examination of the specimens confirmed the diagnosis of osteoblastoma. Five years after surgical treatment, the patient was asymptomatic; CT scan and radiographs showed no local recurrence and complete fusion from C4 to C7 at the left side. This case demonstrates that although rare, spinal osteoid osteoma can progress to osteoblastoma.