Pediatric Infratentorial Ependymoma

  • Etiology: Glial tumor with ependymal differentiation
  • Imaging:
    — Located in floor of fourth ventricle and occasionally into brainstem cisterns via outlets of foramen of Luschaka and foramen of Magendie
    — Ill defined and infiltrative
    — Cysts and calcification in 40-50%
    — Halo secondary to surrounding cerebrospinal fluid
    — Hemorrhage common
    — Can cause obstruction and hydrocephalus
    — Cerebrospinal fluid seeding
  • Imaging MRI:
    — T1WI post contrast: Heterogenous and irregular enhancement
  • DDX: Medulloblatoma arises from roof of fourth ventricle while ependymoma arises from floor of fourth ventricle
  • Complications: Drop metastases via cerebrospinal fluid
  • Treatment:
  • Clinical:

Radiology Cases of Infratentorial Ependymoma

CT and MR of infratentorial ependymoma
Axial CT without contrast of the brain (above left) shows dilation of the lateral ventricles and transependymal flow of cerebrospinal fluid which is due to an ill-defined mass in the midline of the posterior fossa (above right) that is slight calcified and which is obliterating the fourth ventricle. Sagittal TI MRI without contrast of the brain (below left) shows a primarily hypointense mass to be centered in the floor of fourth ventricle. Sagittal T1 with contrast (below middle) shows the mass to have heterogenous enhancement while on axial DWI (below right) there is no diffusion restriction.
MRI of posterior fossa ependymoma
Sagittal T1 MRI without contrast of the brain (left) shows an isointense mass filling and distending the fourth ventricle and exiting it and extending beneath the foramen magnum into the spinal canal. The axial T2 MRI (right) shows the hyperintense mass surrounding the left side of the cervical spinal cord.