Ependymoma

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Ependymoma – immunohistochemical preparation

Ependymoma is a neuroepithelial brain tumor, that occurs along the entire length of the nerve axis in the ventricular space. It most often occurs between 1.–5. year of life, most often intracranially (primarily fourth ventricle). The incidence of spinal ependymomas is prevalent in adult patients (most often between 35–45 years of age). They represent the majority (60 %) of all primary intramedullary tumors.

MRI – subependymom v laterální komoře

It is benign, semi-malignant, there is also a malignant form. It is well demarcated, may contain focal calcification, may bleed. It can grow anywhere in the ventricular system and spinal cord, grows from the lining of the ventricular system from radial glia.

 For more information see Ependymom (pathology).

Localization

1) 60 % posterior cranial fossa,

2) 30 % supratentorially,

3) 10 % spinal cord.

Diagnostics

Ependymomas are primarily diagnosed using CT and MR imaging methods:

• CT – better shows possible calcifications that are present especially in subependymomas,
• MR – ependymomas on MR usually look like well-defined lesions.

Neither edema nor infiltration of the surrounding brain tissue is usually present on both CT and MR. However, as already mentioned in the introduction, in some cases it is possible to see hemorrhage or cystic component.

MRI – myxopapilar ependymoma

Biopsy is often performed to properly determine follow-up treatment.

Classification (according to WHO)

According to the WHO, we divide ependymomas into three groups :

WHO grade I

Division:

• subependymoma – non-invasive, grows slowly, mostly occurs in middle-aged and older patients, often diagnosed incidentally;
• myxopapillary ependymoma – it occurs primarily in the filum terminale and / or in the conus medullaris, represents up to 13% of spinal ependymomas, it is the most common tumor in the cauda equina.

MRI – anaplastic ependymoma

WHO grade II

The "classic" ependymoma is the most common of all types of ependymomas. It occurs primarily intracranially. We divide it into:

• papillary ependymoma;
• clear cell ependymoma;
• tanycytic ependymoma – in addition to intracranial areas, it typically occurs in the cervical and thoracic parts of the spinal cord, but it can also occasionally occur in the filum terminale;
• RELA fusion-positive ependymoma (new classification from 2016).

WHO grade III

Only one form:

• anaplastic ependymoma – has a higher tendency to proliferate, infiltrates the surrounding brain tissue and metastasizes due to spread by cerebrospinal fluid.
  

In addition to the WHO classification, we can distinguish these tumors into low-grade a high-grade ependymomas. Low-grade ependymomas are in their biological nature benign, grow slowly (WHO grade I and II). High-grade ependymomas, which include anaplastic ependymoma (WHO grade III), are malignant, grow rapidly and the prognosis of patients with this tumor is not good.

Symptomatology

Intracranial ependymomas

It primarily depends on the location. In intracranial lesions increased intracranial pressure, headache and related symptoms predominate as the initial presentation. Within the posterior fossa ataxia is common but other symptoms include diplopy, nystagmus etc. Supratentorially, ependymomas are most often manifested by epilepsy, or focal neurological deficits.

Spinal ependymomas

Although there is a relatively diverse symptomatology related to individual tumor localization, back pain, sensory deficits and lower limb weakness generally predominate. Some patients may also have bladder dysfunction, ataxic gait, sphincter disorders or sexual problems. Acute exacerbation of symptoms in some patients may be caused by acute intratumoral haemorrhage and occasionally as a result of spinal subarachnoid haemorrhage hydrocephalus may occur.

Some ependymomas (most commonly WHO grade II, occasionally WHO grade III) are associated with type 2 neurofibromatosis (NF-2) .

Therapy

The basis is the most radical surgical resection. In the case of partial resection, the rest can be irradiated radiosurgically.

Patients (both children and adults) with WHO II or WHO III ependymoma residues are indicated for radiosurgery. It is indicated for chemotherapy, especially in younger children (<12 months) and adult patients with recurrent tumors for whom surgical or radiosurgical treatment is not feasible - it is too risky.

Prognosis

It is not very good, especially due to the location of the tumor, which is often difficult to access surgically. The prognosis is primarily affected by:

1. localization (the most surgically demanding are those in fourth ventricle),
2. anaplastic form of the disease,
3. partial resection.

The probability of 5-year survival in children is around 50-70% but in the case of recurrence, mortality is up to 90%.

• Ependymoma of IV. brain ventricle (MR)
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Diferential diagnostics

The following five diseases are often confused with ependymoma, so the basic differences in their diagnosis are presented:

1. medulloblastoma – it is very similar to the ependymoma, especially due to the localization (IV. ventricle), it grows out of the vermis, it is not so plastic and calcification is not so frequent;
2. papilloma of the chorioid plexus – occurs in children mainly in the trigon of the lateral ventricles and in adults most often in IV. ventricle (this is the opposite typical localization to that of the ependymoma);
3. secondary tumor of the chorioid plexus – on MR very similar, but in the case of a secondary tumor of the choroid plexus, the incidence is more common in elderly patients with a history of malignancy;
4. Glioblastoma multiforme – is more difficult to distinguish especially from intraparenchymal supratentorial ependymoma, glioblastoma is more common in elderly patients and the epicenter of the tumor is the white matter of the brain;
5. central neurocytoma – mostly grows from septum pellucidum.
   

Links

Related articles

• Astrocytom
• Ependymom (pathology)
• Brain gliomas
• Spinal tumors
• Tumors of the CNS
• Oligodendrogliom

Used literature

• ZEMAN, Miroslav, et al. Speciální chirurgie. 2. edition. Praha : Galén, 2004. 575 pp. ISBN 80-7262-260-9.

• ARNAUTOVIĆ, Kenan – GOKASLAN, Ziya. Spinal Cord Tumors. 1. edition. Springer, 2019. 540 pp. ISBN 9783319994383.