Aggressive osteoblastoma involving the craniovertebral junction: A case report and review of literature

Osteoblastoma (OB) is a rare bony neoplasm constituting around 1% of all primary bone tumors. Although the vertebrae and long bones are the most common sites affected by OB, skull remains a relatively uncommon site of occurrence. Aggressive variant of OB is histologically intermediate between an indolent conventional OB and a malignant osteosarcoma. To the best of our knowledge, aggressive osteoblastoma (AO) affecting the craniovertebral junction has not been previously described in the literature. In this report, we present a 34-year-old gentleman who presented with a mass involving the left side of the neck and oral cavity along with ipsilateral lower cranial nerve paresis. Computed tomography and magnetic resonance imaging scans of the craniovertebral junction revealed a heterogeneously enhancing expansile lesion with areas of destruction involving the clivus, left sided jugular foramen and left side of first two cervical vertebras. Angiography showed distortion of the V3 segment of the left vertebral artery and shift of the ipsilateral internal carotid artery. The tumor was maximally excised through far lateral approach. Histopathologic examination revealed a diagnosis of AO. The patient was referred for radiotherapy for the residual tumor and was doing well at 5 months follow-up.