Chondrosarcoma of the Skull Base: A Single-Institution 15-Year Review

Background: Chondrosarcomas are rare malignant cartilaginous tumors that can present in the skull base. They are generally indolent but invasive malignancies. Complete surgical resection is commonly performed when feasible, with adjuvant radiotherapy recommended for intermediate- to high-grade tumors. Studies suggest benefits of subtotal resection with adjuvant therapy to preserve neurovascular structures. Given the rarity of this skull base tumor, our objective was to detail the management and clinical outcomes in a case series of patients with chondrosarcomas of the skull base presenting to our institution over a 15-year period.

Methods: We performed a retrospective review of patients with a pathologic diagnosis of chondrosarcoma of the skull base who received surgical and/or radiotherapy at our institution between 2005 and 2020. Patients were included if their tumor was involving or immediately adjacent to the anterior or lateral skull base. Demographic information, presenting symptoms, tumor characteristics, treatment modalities, and follow-up information were collected via retrospective chart review.

Results: A total of 21 patients met inclusion criteria. 71% were female and the mean age was 49.14 years (range: 25–73). The most common presenting symptoms were visual changes, found in 57% of patients (n = 13). Others included headache (n = 11), sinus symptoms (n = 5), facial numbness/weakness (n = 3), imbalance (n = 3), hearing loss/tinnitus (n = 2), vertigo (n = 1), and dysphagia (n = 1). Two patients presented incidentally on imaging. All had received a preoperative MRI and 17/21 had received a preoperative CT. No patients had nodal, pulmonary, or distant metastasis at the time of diagnosis. All received at least one surgical intervention, with 13 undergoing an endoscopic endonasal resection, 3 an orbitozygomatic craniotomy, 3 a pterional craniotomy, and 4 a different approach. 17 patients underwent a subtotal resection, leaving residual tumor, while 4 had a gross negative resection. On pathology, 33% of tumors were low-grade, 48% were intermediate-grade, 19% were high-grade, and one grade was unknown. Adjuvant radiation was administered to 57% of low-grade, 90% of intermediate-grade, and 100% of high-grade tumors (81% of all patients). 65% of those receiving radiotherapy underwent combined proton/photon therapy, 29% underwent proton therapy alone, and 6% underwent photon therapy alone. Total doses ranged from 70 to 79.2 Gy. No patients received chemotherapy. Two received adjuvant radiation only after developing a local recurrence, one with a low-grade tumor that recurred 35 months after treatment and the other with an unknown tumor grade that recurred 77 months after treatment. 38% developed a new deficit during or after treatment. The average follow-up time was 63 months (IQR: 50–73 months). Estimated 5-year overall and disease-specific survival rates were 95.2 and 100%, respectively.

Conclusion: This case series reviews patients who presented to a tertiary care academic medical center over a 15-year period with chondrosarcoma of the skull base. The primary treatment modality for patients in this cohort was primary surgery with adjuvant radiotherapy for higher grade or residual disease when a gross total resection was not possible. This approach provides excellent local control. Additional study is warranted to evaluate long-term survival and survivorship issues related to treatment of this complex skull base tumor.

Publication History

Article published online:
12 February 2021