title: Supratentorial convexity leptomeningeal schwannoma: case report.
abstract: OBJECTIVE
  Leptomeningeal schwannomas are very rare; to our knowledge, only one case has been previously reported. The possible histogenesis and differential diagnosis of intracranial schwannomas not related to cranial nerves are discussed.
  
  
  METHODS
  A 53-year-old man presented with a sudden onset of seizures. Computed tomographic scans revealed a small hypodense mass in the peripheral aspect of the left frontal lobe. The mass was hypointense on T1-weighted and hyperintense on T2-weighted magnetic resonance imaging scans, with ring enhancement after contrast medium administration.
  
  
  METHODS
  A craniotomy was performed for total removal of the tumor, revealing a well-demarcated, firm, spherical tumor beneath the dura. The tumor was easily separated from the brain. Histologically, the tumor was observed to be within the subarachnoid space, intimately attached to the pia mater. The adjacent brain tissue and dura mater were free of tumor cells. The histological diagnosis was schwannoma.
  
  
  CONCLUSIONS
  Computed tomographic and magnetic resonance imaging findings in our case were consistent with those for a schwannoma, although the subarachnoid space is an extremely rare location for schwannomas. We emphasize that schwannomas may arise in the subarachnoid space.
authors.affiliation: Department of Radiology, Osaka City University Medical School, 1-5-7 Asahimachi, Abeno-ku, Osaka 545-8585, Japan. knakayama@med.osaka-cu.ac.jp
authors.forename: Keiko
authors.initials: K
authors.lastname: Nakayama
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Nakayama
authors.forename: Yoshimi
authors.initials: Y
authors.lastname: Matsuoka
authors.forename: Kinuko
authors.initials: K
authors.lastname: Kono
mesh_terms: D003399:Craniotomy; D003937:Diagnosis, Differential; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008577:Meningeal Neoplasms / Q000175:diagnosis* / Q000473:pathology / Q000601:surgery*; D008875:Middle Aged; D009442:Neurilemmoma / Q000175:diagnosis* / Q000473:pathology / Q000601:surgery*; D014057:Tomography, X-Ray Computed