title: Bilateral internal auditory canal gangliogliomas mimicking neurofibromatosis Type II.
abstract: BACKGROUND
  Gangliogliomas are rare low grade, typically well-differentiated, tumors that are composed of mature ganglion cells and neoplastic glial cells. These tumors can appear at virtually any location along the neuroaxis but classically occur in the temporal lobe of young patients. In a small number of cases, gangliogliomas have presented as masses in the brainstem or involving cranial nerves. With the exception of vestibular schwannomas, bilateral tumors in the region of the internal auditory canal (IAC) or cerebellopontine angle (CPA) are exceedingly rare.
  
  
  METHODS
  We report a case of a 58-year-old male who presented with hearing loss, tinnitus, and vertigo. Initial magnetic resonance imaging revealed bilateral nonenhancing IAC/CPA tumors. Based on this finding, a presumptive diagnosis of neurofibromatosis Type II was made, which was initially managed conservatively with close observation. He returned for follow-up with worsening vertigo and tinnitus, thus prompting the decision to proceed with surgical resection of the symptomatic mass. Intriguingly, pathological study demonstrated a WHO Grade I ganglioglioma.
  
  
  METHODS
  We report a case of a 58-year-old male who presented with hearing loss, tinnitus, and vertigo. Initial magnetic resonance imaging revealed bilateral nonenhancing IAC/CPA tumors. Based on this finding, a presumptive diagnosis of neurofibromatosis Type II was made, which was initially managed conservatively with close observation. He returned for follow-up with worsening vertigo and tinnitus, thus prompting the decision to proceed with surgical resection of the symptomatic mass. Intriguingly, pathological study demonstrated a WHO Grade I ganglioglioma.
  
  
  CONCLUSIONS
  This is the first reported case of bilateral IAC/CPA gangliogliomas. When evaluating bilateral IAC/CPA lesions with unusual imaging characteristics, ganglioglioma should be included in the differential diagnosis.
authors.affiliation: Department of Neurological Surgery, University of Florida, Gainesville, Florida, USA.
authors.forename: Kristopher G
authors.initials: KG
authors.lastname: Hooten
authors.affiliation: Department of Neurological Surgery, University of Florida, Gainesville, Florida, USA.
authors.forename: Seth F
authors.initials: SF
authors.lastname: Oliveria
authors.affiliation: Department of Neurological Surgery, University of Florida, Gainesville, Florida, USA.
authors.forename: Saeed S
authors.initials: SS
authors.lastname: Sadrameli
authors.affiliation: Department of Neurosurgery, North Shore Long Island Jewish, Manhasset, NY, USA.
authors.forename: Shashank
authors.initials: S
authors.lastname: Gandhi
authors.affiliation: Department of Pathology, Immunology, and Laboratory Medicine, University of Florida, Gainesville, Florida, USA.
authors.forename: Anthony T
authors.initials: AT
authors.lastname: Yachnis
authors.affiliation: Department of Neurological Surgery, University of Florida, Gainesville, Florida, USA.
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Lewis
keywords: Bilateral; cerebellar-pontine angle; gangliogliomas; internal auditory canal; tumors