title: Schwannoma arising from the tentorium at an unusual location: case report.
abstract: OBJECTIVE
  We present a case of schwannoma attached to the tentorium.
  
  
  METHODS
  A 41-year-old woman without evidence of neurofibromatosis presented with a 3-month history of headache, positional vertigo, and truncal ataxia. Magnetic resonance imaging revealed an extra-axial cystic mass lesion in the left anteromedial cerebellar region with a dural tail sign.
  
  
  METHODS
  The tumor was removed completely by retrosigmoid craniotomy. Dense adhesion of the tumor to the inferior surface of the tentorium was confirmed during surgery. On light microscopic study, this neoplasm was composed of spindle cells and showed palisaded structures. Immunohistochemically, the tumor cells stained positive for S-100 protein and vimentin. Reticulin staining revealed a pericellular pattern of distribution of reticulin fibers. Electron microscopy confirmed the presence of a basement membrane encompassing the tumor cells. From these findings, the tumor was diagnosed as a schwannoma arising from the tentorium.
  
  
  CONCLUSIONS
  To our knowledge, this case report is the first to describe a schwannoma arising from the tentorium. Our case report indicates that schwannoma is a possible pathology in the differential diagnosis of dura-based tumors.
authors.affiliation: Department of Neurosurgery, Tokyo Metropolitan Ohkubo Hospital, Japan. oikawa-nsu@umin.ac.jp
authors.forename: Akihiro
authors.initials: A
authors.lastname: Oikawa
authors.forename: Naoto
authors.initials: N
authors.lastname: Takeda
authors.forename: Nobuhiko
authors.initials: N
authors.lastname: Aoki
authors.forename: Touichiro
authors.initials: T
authors.lastname: Takizawa
authors.forename: Takaaki
authors.initials: T
authors.lastname: Sakoma
mesh_terms: D000328:Adult; D002528:Cerebellar Neoplasms / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology / Q000601:surgery; D003399:Craniotomy; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008279:Magnetic Resonance Imaging; D008854:Microscopy, Electron; D009442:Neurilemmoma / Q000175:diagnosis* / Q000378:metabolism / Q000473:pathology / Q000601:surgery; D012155:Reticulin / Q000378:metabolism; D009418:S100 Proteins / Q000378:metabolism; D014746:Vimentin / Q000378:metabolism
chemical_list: D012155:Reticulin; D009418:S100 Proteins; D014746:Vimentin