Skull Base Osteosarcoma: An Analysis of 9 Cases and Literature Review

Purpose: Skull base osteosarcoma is an exceedingly rare malignancy. Unlike maxillofacial osteosarcomas, there are only few cases of skull base tumors reported in literature, and their clinical behavior and treatment outcome are not well defined. This study aims to characterize the clinical features and outcomes of primary skull base osteosarcoma based on our experiences of 9 cases and to review available literature data. Methods: A retrospective analysis was done on 9 cases of skull base osteosarcoma diagnosed at IRCCS Istituto Ortopedico Rizzoli, Bologna, Italy, from 1995 to 2023. Clinicopathologic features were reported, and survival outcomes were analyzed. Literature review was performed by searching the PubMed database for published cases of skull base osteosarcoma. Kaplan-Meier survival analysis was used to calculate 1-year, 3-year, and 5-year survival rates. Results: Patients were 5 males and 4 females, with an age range of 5-72 years (mean: 39 years). Tumor location was frontal (3), sphenoid/ethmoid (3), occipital (2), and temporal (1) bone. Seven patients had subtotal resections; Two had total resection, but only one achieved negative margin. Follow-up duration ranged from 4 to 256 months (median: 28 months). Local recurrence occurred in 4 patients. At last follow-up, 5 patients were alive, with 3 had no evidence of disease (NED) and 2 alive with disease (AWD), while 4 patients died of disease (DOD). One-year, 3-year, and 5-year survival were 88.9%, 76.2%, and 57.1%, respectively. Literature review showed 1-year, 3-year, and 5-year survival of 50.3%, 22.6%, and 6.7%, respectively. Conclusion: Skull base osteosarcoma is a rare malignancy with limited data on its clinical behavior. Surgical resection with negative margins is critical for better outcomes but is challenging due to the complex anatomy. Multidisciplinary treatment approaches are essential to improve our understanding of the tumor and survival outcomes.