= GLIOEPENDYMAL CYST = NEUROEPITHELIAL CYST

= rare benign epithelium-lined lesion

Incidence:<1% of all intracranial cysts

Cause: sequestration of developing neural tube elements during embryogenesis

Histo: rounded smooth unilocular cyst lined by ependymal (columnar epithelium) / choroid plexus cells (low cuboidal epithelium) with CSF-like content

Location: anywhere (typically in frontal lobe); intraparenchymal >extraparenchymal

Size: up to several cm in diameter

• typically asymptomatic; symptomatic if CSF flow obstructed
• spherical / ovoid lesion of CSF signal intensity:
  • hyperintense to CSF on T2WI with proteinaceous content
  • smooth rounded borders
• NO enhancement, NO adjacent edema, NO soft-tissue mass, NO gliosis

DDx: choroid plexus cyst (commonly abnormal DWI); arachnoid cyst (typically extraaxial); enlarged Virchow-Robin space (no differentiating feature on imaging, typically multiple + clustered around basal ganglia); porencephalic cyst (communication with lateral ventricle, surrounding gliosis); epidermoid cyst; infectious cyst of neurocysticercosis (<1 cm, partially enhancing)