Massive benign osteoblastoma of the suboccipital bone and foramen magnum region.

Benign osteoblastoma is an uncommon primary bone tumor frequently found in the vertebral column and long tubular bones, and rarely occurring in the calvarium. A case of a massive benign osteoblastoma of the suboccipital bone and foramen magnum region in a 9-year-old boy is reported. He presented with progressively worsening nuchal pain and headaches secondary to a bony lesion in the suboccipital and foramen magnum region. Computed tomography (CT) of the brain showed a large midline occipital/suboccipital bony lesion extending to either side (R > L) and extending from the torcula till the foramen magnum region, causing moderate obstructive hydrocephalus. The atlas was uninvolved by the tumor. In addition, the cerebellum was pushed anteriorly squashing the fourth ventricle. The tumor was completely resected with wide margins via a suboccipital route. At follow-up after 7 years, the patient was asymptomatic, and CT imaging demonstrated no recurrence. The occurrence of benign osteoblastoma in the suboccipital bone and foramen magnum region has not been reported earlier in the pediatric population. Surgical extirpation of the lesion with wide margins is advocated and can produce an excellent long-term outcome. Serial vigilant follow-up along with sequential imaging is advocated even in cases with complete resection to detect early recurrence and possible malignant transformation.