Stereotactic Radiosurgery Induced Malignant Degeneration of a Jugular Foramen Schwannoma: Case Report and Review

Background: The jugular foramen is one of the many apertures of the basal skull that transmits a number of nervous and vascular structures. Tumors of this area comprise less than 1% of all CNS oncology and often cause symptomology related to compression of descending cranial nerves or adjacent brainstem anatomy. Malignant lesions are accepted to be rare. Radiosurgery is often used to treat lesions of this area owing to the challenging surgical approach and importance of structures in this area. The effectiveness of this treatment with minimal side effects has been well documented in the literature.

Method: Case report and literature review.

Results: Here we present a case of stereotactic radiosurgery for a benign schwannoma that developed malignant recurrence 8.5 years later. This report constitutes not only a rare description of a malignant jugular foramen schwannoma, but is the first ever description of a jugular foramen schwannoma undergoing malignant degeneration after radiation therapy. We also review the literature surrounding the clinical, pathological, and radiographic aspects of this case.

Conclusions: Stereotactic radiosurgery is a widely used modality in the treatment of small intracranial lesions. More than 2000 cranial nerve schwannomas have been treated, with only four previously reported cases of associated transformation. Given the extreme rarity of subsequent malignancy, the actual risk to patients appears to remain very low. Regardless, this case does raise a number of questions, including whether radiosurgery is as universally effective and safe for all cranial nerve schwannomas as was traditionally felt, or whether some characteristic more predisposes a lesion to treatment failure and even malignant degeneration.