title: [Microcystic meningiomas: comparison of histology and computed tomography].
abstract: BACKGROUND
  Microcystic meningiomas are defined by large vacuolated and stellate shaped cells. We recently examined a microcystic meningioma mimicking a malignant tumor on computed tomography (CT). The aim of the current study was to compare the radiological features of microcystic meningiomas with their histological patterns.
  
  
  METHODS
  We have diagnosed 7 intracranial microcystic meningiomas among 204 meningiomas registered in the files of our Department of Pathology from 1994 to 2001. All CT scans performed before surgery were reviewed.
  
  
  RESULTS
  Three of the microcystic meningiomas appeared as entirely microcystic tumors. Two of them were homogeneously hypodense or isodense on CT scan. The third mening was heterogeneous, containing some blood. The histologic pattern of the 4 other meningiomas showed microcystic tumor cells associated with meningothelial or fibrous tumor cells. These meningiomas were heterogeneous on CT scan. All meningiomas seemed to be connected to the dura mater. Three tumors were strongly and homogeneously enhanced after contrast media injection while 3 others were heterogeneously enhanced. No enhanced CT scan was available for 1 case. Astrocytomas were incorrectly diagnosed by CT scan in the 3 heterogeneously enhanced tumors. Meningiomas were correctly diagnosed in the 3 strongly enhanced tumors.
  
  
  CONCLUSIONS
  The presence of microcystic tumour cells in meningiomas often results in erroneous diagnosis on CT scan, particularly for those which are heterogeneously enhanced. In these cases, a diagnosis of astrocytoma is often made.
authors.affiliation: Service d'Anatomie Pathologique, Hôpital Bellevue, CHU de Saint-Etienne.
authors.forename: D
authors.initials: D
authors.lastname: Meyronet
authors.forename: R
authors.initials: R
authors.lastname: Mohamedi
authors.forename: A
authors.initials: A
authors.lastname: Gentil-Perret
authors.forename: F-G
authors.initials: FG
authors.lastname: Barral
authors.forename: J
authors.initials: J
authors.lastname: Brunon
authors.forename: J-F
authors.initials: JF
authors.lastname: Mosnier
mesh_terms: D000328:Adult; D003937:Diagnosis, Differential; D004388:Dura Mater / Q000473:pathology; D005260:Female; D006801:Humans; D008297:Male; D008579:Meningioma / Q000000981:diagnostic imaging* / Q000473:pathology*; D008875:Middle Aged; D011379:Prognosis; D016707:Tissue Fixation; D014057:Tomography, X-Ray Computed