Gamma knife treatment of an endolymphatic sac tumor: unique features of a case and review of the literature.

Endolymphatic sac tumors are rare, histologically non-aggressive lesions, but often become locally invasive and lead to erosion of the petrous bone. We report a rare case with multiple endolymphatic sac tumors located at bilateral cerebellopontine angles and vermis of the cerebellum. One of the lesions was surgically resected and others were treated using gamma knife radiosurgery. Local recurrence and metastasis occurred, which was treated with gamma knife radiosurgery. With an appropriate prescription dose and isodose, gamma knife radiosurgery may have an important role in the treatment of endolymphatic sac tumor.