Benign fronto-orbital osteoblastoma arising from the orbital roof: case report and literature review

BACKGROUND: Osteoblastoma is an uncommon benign osteogenic neoplasm that rarely involves the orbit. Intracranial and intraorbital extension causing neurologic and ophthalmologic symptoms and signs is very unusual. We report the case of an osteoblastoma of the orbital cavity with ethmoidal and anterior cranial fossa extension presenting as unilateral proptosis. Manifestations and management of this rare fronto-orbital lesion are discussed, and the relevant literature is reviewed. CASE DESCRIPTION: This 22-year-old man experienced a 3-month history of progressive left proptosis without neurologic symptoms. Computed tomography and magnetic resonance imaging scans demonstrated a bony mass involving the roof of the left orbit and extending laterally to the adjacent ethmoid cells and upward to the lower part of the homolateral frontal convexity without parenchymal abnormality. A presumptive diagnosis of osteoma was considered. A left fronto-orbital craniotomy was performed. At surgery, the tumor was well circumscribed by a sclerotic margin. It was granular with bony spicules, destroying the orbital roof and involving the orbital cavity, ethmoidal cells, and anterior cranial fossa. The lesion was totally removed, and the anterior cranial base reconstructed. The histologic features were typical of benign osteoblastoma. After a follow-up period of 12 months, the patient has remained well without evidence of recurrence. CONCLUSION: Osteoblastoma should be considered in the differential diagnosis with other fronto-orbital bone-forming lesions. Although generally regarded as benign, a complete resection is recommended to prevent the possibility of postoperative recurrence and malignant transformation. Twelve previously reported cases were also reviewed.