An ependymoma is a rare type of brain tumour that develops from the ependymal cells that line the passageways containing cerebral spinal fluid. They are therefore found in the walls of the ventricles or the spinal cord central canal.

Ependymoma can be found in any part of the brain or spine but in children, they are more common in the cerebellum, in an area called the posterior fossa, a small space located at the back of the brain near the brain stem.

Ependymomas represent approximately 1.9% of all primary brain and central nervous system tumours and around 25% of spinal tumours. Ependymomas can also form in the choroid plexus.

Ependymoma brain tumours tend to be diagnosed in children around the age of five years old, and adults of around 45 years. Spinal ependymomas are less common in children and most commonly diagnosed in adults aged around 45 years.

An ependymoma can be classified as a grade 1 or 2 low-grade (slow-growing) tumour or a grade 3 high-grade (malignant) tumour, usually referred to as anaplastic ependymoma.

Low-grade ependymoma tumours (grade 1 and grade 2) are more common in the spine. High-grade or anaplastic ependymomas (grade 3) occur most often in the brain.

Ependymomas are partly classified based on their location in the brain: either supratentorial region or posterior fossa.

They are further divided into distinct molecular subgroups that reflect differences in age of onset, gender predominance, and their expected response to treatment. For example, the most common and aggressive subgroup, posterior fossa ependymoma group A, occurs primarily in young children. Posterior fossa ependymoma group B tumours display more favourable clinical outcomes.

Anaplastic ependymoma

This is classified as a grade 3 ependymoma. ‘Anaplastic’ is a term used to describe a number of different types of tumour, meaning that at this stage the tumour is formed of cancer cells that are dividing rapidly and have little or no resemblance to normal cells.

Cellular ependymoma

A cellular ependymoma is a form of ependymoma that has a particular appearance under a microscope, often with less obvious pseudo-rosette or rosette formation seen amongst the cells when compared to other forms of ependymomas. It is classified as a grade 2 ependymoma.

Clear cell ependymoma

A clear cell ependymoma is a rare form of ependymoma, usually classified as a grade 2 tumour but can also be grade 3. It is named after the way that the cells look under a microscope (a histological classification).

Mxyopapillary ependymoma

A mxyopapillary ependymoma tends to occur in the lower part of the spinal column and is classified as a benign, low-grade or grade I.  

Papillary ependymoma

A papillary ependymoma is a rare form of ependymoma, usually classified as a grade 2 tumour but can also be a grade 3.

Subependymoma

A Subependymoma is a type of ependymoma that has a distinctive appearance under a microscope (histologic variant), and can be found within the supratentorial region (ST) or posterior fossa (PF) regions of the brain. These account for the majority of tumours in the molecular subgroups ST-EPN-SE and PF-EPN-SE, respectively. They are considered to be a benign, low-grade or grade I brain tumour.

Tanycytic ependymoma

A tanycytic ependymoma is a form of grade 2 or grade 3 ependymoma that can be seen to have elongated tanycte cells when viewed under a microscope. Tancytes are common progenitor cells of both ependymal cells and astrocytes: in other words, they could potentially become either an ependymal or an astrocyte cell.