Ependymomas are tumours derived from ependymal cells lining the ventricular system ^[1]. They are classified as neuroepithelial tumours (a subtype of glioma). Although they may appear histologically "low-grade," ependymoma is always considered malignant in paediatrics due to its poor clinical behaviour — because (1) it is slow-growing and hence not chemo-responsive, and (2) the majority are located near the brainstem and cerebellum, making complete resection difficult ^[1].

• Perivascular pseudorosettes: Tumour cells arranged radially around blood vessels with an anuclear zone (the cell processes extend toward the vessel). This is the most characteristic histological feature — present in virtually all ependymomas.
• True ependymal rosettes: Tumour cells forming a ring around a central lumen (mimicking the ependymal canal). Pathognomonic but less frequently seen.
• These features help distinguish ependymoma from other gliomas.

The clinical approach to suspected ependymoma follows the general approach to intracranial tumours ^[3]:

1. Recognise the presentation pattern: ↑ICP ± focal neurological deficits ± seizures
2. Localise the lesion: Posterior fossa vs supratentorial vs spinal
3. Consider age: Child with posterior fossa mass → think medulloblastoma, pilocytic astrocytoma, ependymoma
4. Image: MRI brain ± spine with contrast (gold standard)
5. Tissue diagnosis: Surgical resection (therapeutic + diagnostic)
6. Molecular classification: WHO CNS5 integrated diagnosis
7. Stage: Craniospinal MRI + CSF cytology to assess for dissemination

1. Definition: Primary CNS neoplasm from ependymal cells lining the ventricular system / central canal
2. Epidemiology: Peak age 6y in children; 70% posterior fossa in paediatrics ^[1]; spinal ependymoma commonest intramedullary tumour in adults (peak 30-40y)
3. Risk factors: Ionising radiation (only proven environmental factor), NF2, FAP/Turcot syndrome
4. Pathophysiology: Mass effect → ↑ICP (CSF obstruction), cerebellar/brainstem compression, CSF drop metastases; extracranial metastasis is rare (no lymphatics)
5. Classification: WHO CNS5 → anatomical + molecular (PFA, PFB, ZFTA-RELA, YAP1, myxopapillary, MYCN-amplified)
6. Histology: Perivascular pseudorosettes (most characteristic), true ependymal rosettes (pathognomonic)
7. Clinical features: Children → ↑ICP (headache worse in AM, vomiting, papilloedema) + cerebellar signs (ataxia, nystagmus) + CN palsies; Spinal → segmental pain + central cord syndrome
8. Ependymoma is always considered malignant in paediatrics ^[1] — slow-growing (not chemo-responsive), dangerous location
9. Chemotherapy alone has NO role in ependymoma ^[1]
10. Management cornerstone: Maximal safe surgical resection (1st line) ± adjuvant radiation therapy

Medulloblastoma occurs exclusively in the cerebellum in the midline cerebellar vermis ^[8][9], while ependymoma characteristically arises from the floor of the 4th ventricle (ependymal surface) and may extend laterally through the foramina of Luschka into the cerebellopontine angle. Pilocytic astrocytoma typically presents as a cystic mass with an enhancing mural nodule in the cerebellar hemisphere. These imaging patterns are key differentiators.

A crucial radiological distinction in brain tumour DDx:

• Extra-axial = outside brain parenchyma (e.g. meningioma, schwannoma) — these displace brain, widen CSF spaces, have a "CSF cleft" sign
• Intra-axial = within brain parenchyma (e.g. gliomas, metastases, ependymoma arising from ventricular lining and growing into parenchyma)

This distinction narrows the differential immediately.

Although ependymomas are classically intraventricular, supratentorial ependymomas can occasionally be paraventricular or even in the suprasellar region. Craniopharyngiomas also occur suprasellarly and can have calcification — a feature shared with ependymomas. The key differentiator is that craniopharyngiomas arise from Rathke's pouch remnants (ectodermal origin), are extra-axial, and present with endocrine dysfunction, whereas ependymomas arise from ependymal cells (neuroepithelial origin) and are intra-axial/intraventricular.

Both present with gradual onset segmental pain ± neurological deficit of central cord pattern ^[3]. However:

• Ependymoma tends to be central, well-circumscribed, and often has a characteristic "haemosiderin cap" (dark rim on T2-weighted MRI from chronic micro-haemorrhage at tumour poles) — this is nearly pathognomonic. Gross total resection is often achievable.
• Astrocytoma tends to be eccentric, infiltrative, ill-defined, making GTR much harder. The pathology is lower grade than in brain but still infiltrative → complete excision less likely ^[3].

1. The "Big Three" posterior fossa tumours in children: Medulloblastoma (vermis, highly chemo-sensitive, drops mets), Pilocytic astrocytoma (hemisphere, cystic + mural nodule, excellent prognosis), Ependymoma (4th ventricle floor, extends through foramina, chemo-resistant)
2. Key imaging differentiators: Ependymoma = heterogeneous, calcified, "plastic" tumour extruding through foramina. Medulloblastoma = homogeneous, restricted diffusion. Pilocytic astrocytoma = cystic + enhancing mural nodule
3. Spinal cord DDx: Ependymoma (central, haemosiderin cap, well-circumscribed) vs Astrocytoma (eccentric, infiltrative, ill-defined)
4. Histological diagnosis by surgical biopsy is mandatory to differentiate ependymoma from other tumours ^[8][9] — markers alone cannot distinguish it
5. Brain metastasis is the commonest intracranial tumour in adults ^[10] — always consider metastasis in an adult with a brain mass
6. CN VI palsy in a child = false localising sign of raised ICP ^[13] → investigate for posterior fossa tumour
7. Secondary tumours are 6–10× more common than primary brain tumours ^[2]

1. CT is the emergency imaging modality — fast (1 minute), widely available, excellent for detecting hydrocephalus, haemorrhage, and calcification. However, MRI with contrast is generally preferred over CT ^[3][14] for definitive tumour characterisation.
2. Never perform lumbar puncture if there is a posterior fossa mass with hydrocephalus — risk of tonsillar herniation through the foramen magnum (coning).
3. Staging of the entire craniospinal axis is mandatory before surgery — because ~10% of ependymomas have leptomeningeal dissemination at diagnosis ^[8][9], and the surgeon needs to know the full extent of disease.
4. Surgery is both diagnostic and therapeutic — maximal safe removal as 1st line in all operable gliomas ^[1].

1. There are no formal clinical diagnostic criteria — diagnosis is based on neuroimaging + histopathological confirmation + molecular profiling (WHO CNS5 integrated diagnosis)
2. Histological examination of biopsy specimen remains the most important component of diagnostic evaluation ^[8][9]
3. CT: first-line emergency imaging; look for calcification (~50%), hydrocephalus, mass in 4th ventricle
4. MRI with contrast is preferred over CT ^[3][14] — better soft tissue delineation, especially at brainstem/skull base
5. Key MRI features of ependymoma: heterogeneous enhancement, arises from 4th ventricle floor, extends through foramina ("plastic"), calcification; in spine: central, well-circumscribed, haemosiderin cap
6. DWI distinction: Ependymoma = no marked diffusion restriction; Medulloblastoma = prominent restriction (high cellularity); Primary CNS lymphoma = prominent restriction
7. Staging: Craniospinal MRI + CSF cytology. Extracranial staging is NOT routine (no lymphatic drainage → TNM staging not useful)
8. Functional MRI and DTI tractography are used for pre-operative planning ^[11]
9. Molecular markers: H3K27me3 loss (PFA), L1CAM/RELA fusion (supratentorial), MYCN amplification (spinal aggressive), DNA methylation profiling (gold standard)
10. AFP/β-HCG should be normal — if elevated, think germ cell tumour instead

Chemotherapy works by exploiting the rapid cell division of malignant cells — agents like vincristine, cisplatin, and cyclophosphamide damage DNA or disrupt mitosis, preferentially killing cells in S-phase or M-phase. Ependymoma is slow-growing and hence not chemo-responsive ^[1]. The proportion of cells actively dividing (the "growth fraction") is low, so chemotherapy has limited targets. This is fundamentally different from medulloblastoma (a highly cellular embryonal tumour with a high growth fraction), where chemotherapy is effective.

The exception: chemotherapy may be used as a temporizing measure in very young children (< 3 years) to delay radiotherapy — not because it is effective against the tumour per se, but to spare the developing brain from the devastating neurocognitive effects of cranial irradiation. Even in this setting, chemotherapy is not expected to cure the disease.

1. Maximal safe surgical resection is 1st line in all operable gliomas ^[1][3][16] — GTR is the strongest prognostic factor
2. External RT as 2nd line if not operable ^[1] — adjuvant focal RT is standard for most intracranial ependymomas post-surgery
3. Chemotherapy alone has NO role in ependymoma ^[1] — fundamentally different from medulloblastoma
4. Emergency management: Dexamethasone 10mg then 4mg Q4H ^[16] for peritumoral oedema; EVD/ETV for acute hydrocephalus
5. Do NOT give steroids if CNS lymphoma is in the differential — steroid causes acute lysis of lymphocytes → ↓ diagnostic yield on biopsy ^[16]
6. Anticonvulsants (levetiracetam) for seizures — NOT for infratentorial lesions, usually not for primary prophylaxis ^[16]
7. Posterior fossa syndrome (cerebellar mutism) is a recognised post-operative complication ^[8][9]
8. Late effects of RT: ↓GH (94%), ↓ACTH (43%), ↓TSH (10%), ototoxicity, neurocognitive impairment, cerebrovascular abnormalities ^[8][9]
9. Delay RT in infants < 3 years to protect the developing brain; use chemotherapy as a temporising bridge
10. Long-term surveillance with serial MRI is mandatory — ependymoma can recur years to decades later

1. Most common presenting complication: Obstructive hydrocephalus from 4th ventricle obstruction → raised ICP → potential for fatal brain herniation
2. Around 10% of ependymomas have leptomeningeal spread ^[8][9] — always stage with craniospinal MRI
3. Posterior fossa syndrome (cerebellar mutism): appears 1–2 days post-surgery, caused by injury to cerebellar vermis/dentate nuclei, characterised by impaired language production + emotional lability, resolves over weeks–months ^[8][9]
4. Late effects of RT are the most significant long-term complications: ↓GH (94%), ↓ACTH (43%), ↓TSH (10%), ototoxicity, neurocognitive impairment, cerebrovascular abnormalities ^[8][9]
5. Childhood cancer paradox: 70% of children survive but have extensive long-term complications ^[17] — lifelong surveillance for endocrine, cognitive, hearing, and second malignancy screening is mandatory
6. Recurrence rate ~30–50%, mostly local — aggressive re-resection is still advocated
7. Secondary malignancy from RT (meningioma, glioma) — latency > 10 years
8. Seizures are always supratentorial ^[16] — do not expect seizures from posterior fossa ependymoma