CNS Tumors in Children: Astrocytoma, Medulloblastoma, Ependymoma, Germinoma, Craniopharyngioma

Symptoms & signs · Diagnosis · Principles of treatment · Glial tumors (astrocytoma, brainstem, ependymoma, choroid plexus) · Embryonal tumors (medulloblastoma, supratentorial PNET, pineal) · Intracranial germ cell tumors · Craniopharyngioma
🧠 Key concepts: Raised ICP (morning headache, vomiting, papilloedema), cerebellar signs (ataxia, nystagmus), focal deficits. MRI is imaging gold standard. Medulloblastoma (posterior fossa, 4th ventricle, leptomeningeal spread). Pilocytic astrocytoma (good prognosis). Brainstem glioma (diffuse intrinsic poor prognosis). Craniopharyngioma (suprasellar, calcification).

📖 CNS tumors: classification, presentation & treatment

🧠 Glial tumors
Pilocytic astrocytoma (cerebellum, optic pathway, good prognosis). Diffuse astrocytoma (malignant). Brainstem glioma – DIPG (diffuse intrinsic pontine glioma, poor outcome). Ependymoma (4th ventricle, drop metastases). Choroid plexus papilloma/carcinoma.
🌀 Embryonal tumors
Medulloblastoma (most common malignant brain tumor, posterior fossa, desmoplastic vs classic, WNT, SHH, group 3/4). Supratentorial PNET (rare). Pineal tumors (pineoblastoma, germ cell).
🧬 Germ cell tumors & craniopharyngioma
Intracranial GCT: germinoma (most common, pineal/suprasellar), teratoma, yolk sac (AFP), choriocarcinoma (β-hCG). Craniopharyngioma (suprasellar, cystic, calcified, endocrine deficits, visual loss).
⚠️ Red flags for brain tumor: Morning headache with vomiting, progressive headache, focal neurology (hemiparesis, cranial nerve palsy), seizures, ataxia, visual disturbance, growth failure (endocrine), early morning vomiting without nausea.

🩺 Symptom-based approach to pediatric CNS tumors

1
Raised intracranial pressure (ICP) – Headache (worse in morning, with vomiting), papilloedema, abducens palsy (false localising), nausea, vomiting (may be projectile). Infants: bulging fontanelle, increasing head circumference, sunsetting eyes.
2
Posterior fossa tumors (medulloblastoma, cerebellar astrocytoma, ependymoma) – Truncal ataxia, nystagmus, hypotonia, head tilt, early morning vomiting (4th ventricle compression).
3
Suprasellar tumors (craniopharyngioma, optic glioma, germinoma) – Visual field defects (bitemporal hemianopia), endocrine deficits (growth failure, diabetes insipidus, hypopituitarism), precocious puberty (germinoma).
4
Brainstem tumors (DIPG) – Cranial nerve palsies (CN VI, VII, lower cranial nerves), long tract signs (hemiparesis, hyperreflexia), ataxia, often normal ICP early.
5
Diagnostic imaging – MRI brain with contrast is gold standard (assess location, enhancement, hydrocephalus, leptomeningeal spread). CT for acute haemorrhage/calcification (craniopharyngioma).
📌 Clinical pearl: A child with morning headache and vomiting that improves during the day suggests raised ICP. Papilloedema is a late sign in children. Urgent neuroimaging before lumbar puncture.

📋 Principles of treatment for pediatric CNS tumors

1
Emergency management of raised ICP – Dexamethasone (0.5-1 mg/kg/day), emergent CSF diversion (EVD, ETV) if hydrocephalus. Avoid LP before imaging.
2
Surgery – Maximal safe resection. Gross total resection improves outcome for cerebellar astrocytoma, ependymoma, craniopharyngioma. Biopsy for DIPG (not usually resected).
3
Radiotherapy – Craniospinal irradiation (CSI) for medulloblastoma, germinoma, ependymoma (local). Proton therapy reduces late effects. Avoid RT in infants <3 years.
4
Chemotherapy – Medulloblastoma: cisplatin, vincristine, cyclophosphamide, lomustine. Low-grade glioma: carboplatin, vincristine (delay RT). High-grade glioma: temozolomide. Germinoma: platinum/etoposide (responsive).
5
Targeted therapy & clinical trials – BRAF inhibitors (pilocytic astrocytoma with BRAF fusion). Sonic hedgehog inhibitors (medulloblastoma). DIPG: re-irradiation, ONC201, trials.
6
Long-term follow-up – Endocrine (GH deficiency, hypothyroidism), neurocognitive (especially after CSI), hearing (platinum), ophthalmology, psychosocial support.
🚨 Avoid LP in suspected brain tumor until imaging excludes mass effect; LP can cause transtentorial herniation. Dexamethasone before surgery reduces peritumoral oedema.

🧠 Reflex prompts: CNS tumors

🧠 6-year-old with morning headache, vomiting, ataxia. MRI shows midline posterior fossa mass enhancing with contrast. Likely diagnosis?
Medulloblastoma (PNET). CSF staging (leptomeningeal spread). Craniospinal irradiation + chemotherapy.
🩺 4-year-old with progressive ataxia, head tilt, and cystic cerebellar mass on MRI. Most likely?
Pilocytic astrocytoma (WHO grade I). Gross total resection is curative.
👁️ 8-year-old with bitemporal hemianopia, growth failure, and suprasellar calcification on CT. Diagnosis?
Craniopharyngioma (adamantinomatous). Surgery, +/- radiotherapy.
🧬 Child with diabetes insipidus, visual loss, and pineal/suprasellar mass with elevated β-hCG in CSF. Diagnosis?
Intracranial germ cell tumor (germinoma or choriocarcinoma). Chemosensitive, radiosensitive.
🩺 5-year-old with cranial nerve VI and VII palsy, right hemiparesis, and pontine T2 hyperintense mass without enhancement. Diagnosis?
Diffuse intrinsic pontine glioma (DIPG). Poor prognosis; radiotherapy primary treatment.
🧬 Which molecular subgroup of medulloblastoma has the best prognosis?
WNT-activated (CTNNB1 mutation). TP53 mutant SHH has worst prognosis.
💊 First-line chemotherapy for a young child with optic pathway glioma (NF1-associated)?
Carboplatin + vincristine (to delay/avoid radiotherapy).
🧪 Which tumor marker is elevated in CSF/serum of patients with yolk sac tumor (intracranial germ cell)?
Alpha-fetoprotein (AFP).
🩺 What is the most common malignant brain tumor in children?
Medulloblastoma (followed by pilocytic astrocytoma, ependymoma).
🧠 What is the standard of care for a child with newly diagnosed DIPG (diffuse midline glioma)?
Focal radiotherapy (54-60 Gy). No survival benefit from chemotherapy. Clinical trials for novel agents.