title: [Association of an arachnoid cyst with heterotopic neuroglial tissue in the internal auditory canal].
abstract: OBJECTIVE
  We report a case of an association of an arachnoid cyst with heterotopic neuroglial tissue in the internal auditory canal.
  
  
  METHODS
  A 66-year-old woman consulted for cochleovestibular syndrome.
  
  
  RESULTS
  MRI demonstrated a lesion with spontaneous hypersignal on T1- and T2-weighted images, instigating surgical exploration. We discovered a hematic arachnoid cyst associated with heterotopic neuroglial tissue arising in the internal auditory canal.
  
  
  CONCLUSIONS
  An arachnoid cyst arising within the cerebellopontine angle or the internal auditory canal is a rare occurrence. Clinical manifestations are identical with those produced by a cochleovestibular schwannoma. MRI usually demonstrates a nonenhancing isointense cystic mass with cerebrospinal fluid on all sequences (hypointense on T1-weighted and hyperintense on T2-weighted images). These lesions are usually monitored. Spontaneous hypersignal on T1- and T2-weighted images makes diagnosis difficult, as in our case, leading to surgical exploration.
authors.affiliation: Service d'ORL, hôpital Lariboisière, AP-HP, faculté de médecine, université de Paris Diderot-Paris 7, 2, rue Ambroise-Paré, 75010 Paris, France.
authors.forename: K
authors.initials: K
authors.lastname: Aubry
authors.forename: M
authors.initials: M
authors.lastname: Wassef
authors.forename: J-P
authors.initials: JP
authors.lastname: Guichard
authors.forename: P
authors.initials: P
authors.lastname: Herman
authors.forename: P
authors.initials: P
authors.lastname: Tran Ba Huy
mesh_terms: D000368:Aged; D016080:Arachnoid Cysts / Q000150:complications* / Q000175:diagnosis / Q000601:surgery; D002530:Cerebellopontine Angle / Q000473:pathology; D002828:Choristoma / Q000150:complications* / Q000175:diagnosis / Q000601:surgery; D003937:Diagnosis, Differential; D007758:Ear, Inner / Q000473:pathology*; D005260:Female; D006314:Hearing Loss, Conductive / Q000209:etiology; D006801:Humans; D008279:Magnetic Resonance Imaging; D009457:Neuroglia; D014012:Tinnitus / Q000209:etiology; D016896:Treatment Outcome; D014717:Vertigo / Q000209:etiology