Title

Malignant transformation of a vestibular schwannoma after gamma knife radiosurgery.

Department

Neurosurgery; Pathology

Document Type

Article

Abstract

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 cm(3)).

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.

Medical Subject Headings

Brain Stem Neoplasms; Cell Transformation, Neoplastic; Craniotomy; Facial Paralysis; Fatal Outcome; Female; Humans; Ki-67 Antigen; Magnetic Resonance Imaging; Middle Aged; Neoplasm Recurrence, Local; Nervous System Diseases; Neuroma, Acoustic; Postoperative Complications; Radiosurgery

Publication Date

3-1-2013

Publication Title

World Neurosurg

ISSN

1878-8769

Volume

79

Issue

3-4

First Page

1

Last Page

8

PubMed ID

22480982

Digital Object Identifier (DOI)

10.1016/j.wneu.2012.03.016

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