Malignant transformation of a vestibular schwannoma after gamma knife radiosurgery

Vijay Yanamadala, Richard W. Williamson, David J. Fusco, Jennifer Eschbacher, Peter Weisskopf, Randall W. Porter

Research output: Contribution to journalReview articlepeer-review

30 Scopus citations


Objective: To report a single case of malignant transformation of a vestibular schwannoma after radiosurgery and review the growing body of literature describing patients with malignant transformation of primary benign tumors after radiosurgery, including vestibular schwannoma. Methods: A 46-year-old woman presented with right facial paresthesias and imaging consistent with a right-sided vestibular schwannoma (volume approximately 18.5 cm3). Results: The patient underwent subtotal resection followed by Gamma Knife radiosurgery (GKRS) 6 months after surgery. Initial histology showed a benign vestibular schwannoma with an MIB-1 labeling index of 5.7%. At 43 months after GKRS, the patient underwent repeat subtotal resection of a benign vestibular schwannoma (MIB-1 labeling index 7.4%). At 59 months after GKRS, she underwent a third resection, and histology showed frank malignant transformation (MIB-1 labeling index 33.8%). Conclusions: Malignant vestibular nerve tumors are extremely rare; only 18 cases have been reported in the literature. Our patient is the sixth pathologically confirmed case of malignant transformation after radiosurgery, supporting the contention that radiosurgery itself may play a causative role in transformation. In a histologically benign lesion, the presence of an elevated MIB-1 labeling index may predispose toward malignant transformation in the setting of adjuvant radiosurgery.

Original languageEnglish (US)
Pages (from-to)593.e1-593.e8
JournalWorld neurosurgery
Issue number3-4
StatePublished - 2013


  • Gamma Knife
  • Malignant
  • Radiation
  • Schwannoma

ASJC Scopus subject areas

  • Surgery
  • Clinical Neurology


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