Intracranial ependymoma diagnosis

The majority of intracranial ependymomas (60%) are located in the posterior fossa (infratentorial), usually arising from the lateral recess of the fourth ventricle (molecular subgroup: Posterior fossa type A Ependymoma) and midline inferior floor of the fourth ventricle near the obex (molecular subgroup: Posterior Fossa B) ^{1) 2) 3) 4)}

The remainder (40%) are located supratentorially and up to half of these are intraparenchymal.

see Supratentorial ependymoma.

In contrast to spinal cord ependymomas, calcification is common.

Posterior fossa ependymomas are apt to extend through the foramen of Luschka and foramen of Magendie, hence the term plastic ependymoma. This is a characteristic feature and can be seen on both CT and MRI.

Ependymomas are typically heterogeneous masses with areas of necrosis, calcification, cystic change and hemorrhage frequently seen. This results in a heterogeneous appearance on all modalities.

Intraparenchymal lesions (usually supratentorial) are generally large and variable in appearance, ranging from completely solid, enhancing masses to cysts with a mural nodule, or more heterogeneous masses.

Coarse calcification is common (50%)

Cystic areas (50%)

Solid component iso- to hypodense

Heterogeneous enhancement

Variable hemorrhage

see Intracranial ependymoma MRI.