title: Midline "brain in brain": an unusual variant of holoprosencephaly with anterior prosomeric cortical dysplasia.
abstract: BACKGROUND
  We report three cases of brain malformation presenting with a midline mass of dysplastic cortex that we have termed "brain in brain" malformation.
  
  
  RESULTS
  The three cases have holoprosencephalic features, including bilateral hemispheric continuity across the midline, single ventricle, midline facial defect and missing olfactory bulbs. All three cases have a midline conglomerate mass of deeply infolded, cortex-lined fissures with major arterial branches, heterotopia and large amount of white matter. The dysplastic mass of cortex and white matter extended into the third ventricle. The cortex and white matter of the dysplastic lesion was continuous with the cortex and white matter, respectively, of the cerebral hemispheres.
  
  
  CONCLUSIONS
  The midline "brain in brain" malformations have some similarities to subcortical heterotopia and extracerebral glioneuronal heterotopia. However, the continuity with the cerebral hemispheres and extension into the ventricle were not reported in subcortical or glioneuronal heterotopia. The common involvement of the midline cortex and extension into the third ventricle implied an anterior segmental prosencephalic abnormality (prosomeres 5/6). However, its pathogenesis remains to be explained.
authors.affiliation: Division of Neuroradiology, Hospital for Sick Children, Toronto, Ontario, Canada.
authors.forename: E
authors.initials: E
authors.lastname: Widjaja
authors.forename: L
authors.initials: L
authors.lastname: Massimi
authors.forename: S
authors.initials: S
authors.lastname: Blaser
authors.forename: C
authors.initials: C
authors.lastname: Di Rocco
authors.forename: C
authors.initials: C
authors.lastname: Raybaud
mesh_terms: D002540:Cerebral Cortex / Q000473:pathology*; D005260:Female; D016142:Holoprosencephaly / Q000473:pathology*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007232:Infant, Newborn, Diseases / Q000473:pathology*; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed