Background: Osteosarcoma of the skull base is a rare disease but carries a poor prognosis. Surgery and adjuvant therapy are treatment options for osteosarcoma. Due to vital nearby anatomy, gross-total resection is difficult and is potentially associated with high morbidity. Here, we review two unique cases of skull base tumors mimicking skull base osteosarcoma.
Methods: Two patients with deemed unresectable osteosarcoma of the anterior/middle skull base who were treated with chemotherapy at outside institutions were identified. Given relatively poor response, the patients were referred for Proton beam radiation therapy. Due to the disease extent, the patients were sent to our institution for surgical consideration prior to radiation. Final pathologic findings following surgical resection are reviewed.
Results: The patients include a 23-year-old female diagnosed with clival osteosarcoma following endoscopic biopsy. The patient had received chemotherapy with minimal response. Endoscopic endonasal gross-total resection was then completed. Pathology revealed a giant cell rich neoplasm. The second patient was a 47-year-old male diagnosed with anterior skull base chondroblastic osteosarcoma status post chemotherapy with minimal response. A gross-total resection was achieved via an endoscopic anterior craniofacial resection. Final pathology was reported as grade 1 chondrosarcoma.
Conclusion: Osteosarcoma of the skull base is a rare diagnosis and is difficult to treat. Accurate pathologic diagnosis is imperative and often a large sample size is required. When response to chemotherapy is poor, the possibility of an alternative diagnosis should be considered. Endoscopic endonasal surgery by an experienced skull base surgery team is feasible and may facilitate the diagnosis and treatment of these lesions.