Supratentorial ependymomas are a type of location-specific ependymomas. They account for 30% of ependymomas, and in most instances are within or abutting the ventricles (third and fourth ventricles). In approximately 40% of cases they are remote from the ventricular surface, located within the parenchyma of the hemispheres.
They usually present with headache, seizures and focal neurological deficits compared to infratentorial counterparts which mainly present with features of raised intracranial pressure.
Share similar pathological spectrum to posterior fossa ependymomas, with the exception that the RELA fusion-positive ependymoma subtype is usually supratentorial, and not found in the posterior fossa .
Radiologically they are similar to ependymomas in other locations.
- coarse calcification is common (50%)
- cystic areas (50%)
- solid component iso to hypodense
- heterogeneous enhancement
- a small proportion can have hemorrhage
- noncontrast CT appearances of an intraparenchymal ependymoma could resemble periwinkle flower, called periwinkle sign .
- solid portions of ependymoma typically are isointense to hypointense relative to white matter
- hyperintense to white matter
- more reliable in differentiating tumor margins than non-contrast T1-weighted images (but less reliable than contrast enhanced T1)
- T2* (e.g. SWI)
- foci of blooming from hemorrhage of calcification
- T1 C + (Gd)
- enhancement present but heterogeneous
- enhancement with gadolinium is useful in differentiating tumor from adjacent vasogenic edema and normal brain parenchyma
- restricted diffusion may be seen in solid components especially in anaplastic tumor
- diffusion should be interpreted with caution in masses with significant hemorrhage or calcification
The imaging findings can remembered as “1234 rule” :1 stands for a single large tumor common in the first decade, 2P for Perilesional edema and Periwinkle sign, 3L for Large Lobulated Lobar mass and 4C for Central Chunky Calcification and large peripheral Cyst
Treatment and prognosis
Supratentorial ependymomas generally have a somewhat better prognosis than their more common posterior fossa counterparts. This is especially the case in children .
Imaging differential considerations depend on whether the tumor is within the ventricle or parenchymal.
For intraventricular supratentorial tumors consider:
For parenchymal tumors consider:
- anaplastic astroctyomas, oligodendroglioma and glioblastoma
- primitive neuroectodermal tumors (PNET)
- cerebral metastases
- supratentorial anaplastic ependymomas
- primitive neuroectodermal tumours (pnet)