Grading of meningiomas follows the WHO classification for CNS tumors and ... infiltration into the brain parenchyma of an otherwise "benign" grade I tumor was ...×ArticlesLogInCasesSignUpCoursesQuizBlogDonateAbout×MenuSearchADVERTISEMENT:Radiopaediaisfreethankstooursupportersandadvertisers.BecomeaGoldSupporterandseenoads.ArticlesCasesCoursesLogInLoginSignup{"url":"/signup-modal-props.json?lang=us\u0026email="}ArticlesCasesCoursesQuizAboutBlogGoad-freeSearchMeningiomaDrBahmanRasuli◉andAssocProfFrankGaillard◉◈etal.Meningiomasareextra-axialtumorsandrepresentthemostcommontumorofthemeninges.Theyareanon-glialneoplasmthatoriginatesfromthemeningocytesorarachnoidcapcellsofthemeningesandarelocatedanywherethatmeningesarefound,andinsomeplaceswhereonlyrestcellsarepresumedtobelocated. Althoughtheyareusuallyeasilydiagnosedandaretypicallybenignwithalowrateofrecurrencefollowingsurgery,therearealargenumberofhistologicalvariantswithvariableimagingfeaturesand,insomeinstances,moreaggressivebiologicalbehavior.Abroaddivisionofmeningiomasisintoprimaryintradural(whichmayormaynothaveasecondaryextraduralextension)andprimaryextradural(rare) 18.Theycanalsobeclassifiedaccordingtothelocation(e.g.spinal,intraosseous, intraventricular,etc.),byhistologicalvariants(e.g.clearcell,rhabdoid,etc.),andbyetiology(e.g.radiation-induced,etc.).Typicalmeningiomasappearasdural-basedmassesisointensetogreymatteronbothT1andT2weightedimagingenhancingvividlyonbothMRIandCT.Someofthevariantsasmentionedearliercan,however, varydramaticallyintheirimagingappearance.Thisarticleisageneraldiscussionofmeningiomafocusingontypicalprimaryintraduralmeningiomasandtheimagingfindingsofintracranialdisease. Forspinalandprimaryextraduraltumorsrefertospinalmeningioma andprimaryextraduralmeningiomaarticlesrespectively.Manyofthehistologicalvariantsarealsodiscussedseparately. Rarely(e.g.1-2%ofcases27)meningiomasmayalsoariseatectopicsites(ectopicprimarymeningioma)suchasinheadandneck,orbit,nose,paranasalsinus,oropharynxandevenplacessuchasthe