A Systematic Review of Skull Base Osteoblastoma: Clinical Features, Treatment, and Outcomes

Objective: Osteoblastoma is a solitary, vascular osteoid-forming bone tumor that is rich in osteoblasts, comprising approximately 3.5% of all benign primary bone tumors. It involves the head in 13 to 21% of total cases, with only 2 to 4% arising in the cranium. Osteoblastoma can be subcategorized into two groups: benign osteoblastoma and aggressive osteoblastoma. Aggressive osteoblastoma is much more rare, locally aggressive, and destructive, and histologically intermediate between benign osteoblastoma and osteosarcoma. Because of its rarity, studies examining the clinical features and the relationship between treatment and clinical outcomes of osteoblastoma are limited. Here, we systematically analyze clinical features, radiologic characteristics, and treatment strategies and outcomes for skull base osteoblastoma. In addition, we analyze and compare the treatment and outcomes differences between the two subtypes of osteoblastoma to determine whether each subtype needs to be treated differently. Material and Methods: A comprehensive review identified reported cases of osteoblastoma of the skull base in the English literature. Articles were screened for duplication, and duplicates were excluded. Results: A total of 71 unique cases of benign osteoblastoma and 9 unique cases of aggressive osteoblastoma were identified. The average age at presentation of benign osteoblastoma is 22 years, with a range of 7 months to 78 years. Overall, 77% of the cases occurred in patients younger than 30 years. The male-to-female ratio is 1:1. The average age at presentation of aggressive osteoblastoma is 31 years, with a range of 12 to 69 years and male-to-female ratio of nearly 1:1. Overall, the most common bone of origin is the temporal bone (36%) followed by the frontal bone (18%). The average duration of symptoms is 17 months. The recurrence rates for benign osteoblastoma are 10 and 33% for gross total resection and subtotal resection, respectively. The recurrence rate for aggressive osteoblastoma is 33% after gross total resection and 57% overall. Conclusion: Our data suggest that gross total resection results in a lower recurrence rate for both benign and aggressive osteoblastoma of the skull base. This critical finding is heightened by the fact that most skull base osteoblastoma occur in young patients. Surgical therapy for skull base osteoblastoma may be optimized to aim for maximal resection to minimize risk of recurrence. Although it would appear that more aggressive surgical treatment is needed for aggressive osteoblastoma, there have only been a few reported cases thus far and a larger series is needed before making such a recommendation.