Overview - The Little Brains
- Most common solid tumors in childhood & the second most common malignancy after leukemia.
- Primary tumors are more frequent than metastases.
- Location is key: ~70% are infratentorial (posterior fossa), unlike adult tumors which are mainly supratentorial.
- Presents with signs of ↑ Intracranial Pressure (ICP):
- Morning headaches, often occipital
- Projectile vomiting without nausea
- Papilledema (late sign)
⭐ The most common pediatric brain tumor is Pilocytic Astrocytoma (WHO Grade I), typically found in the cerebellum.
Clinical Features - Telltale Signs
- Signs of ↑ Intracranial Pressure (ICP): The most common presentation.
- Headache: Classically worse on waking, improves after vomiting.
- Vomiting: Often projectile, without nausea.
- Papilledema: Optic disc swelling on fundoscopy.
- Cushing's Triad (Late): Hypertension, bradycardia, irregular respiration.
- Age-Specific Signs:
- Infants: Macrocephaly, bulging fontanelle, suture diastasis, "sunsetting" sign.
- Older Children: School failure, personality changes, growth failure.
- Location-Specific Signs:
- Cerebellar: Ataxia, Nystagmus, Dysmetria (📌 A.N.D.).
- Supratentorial: Seizures, hemiparesis, visual field defects.
- Brainstem: Multiple cranial nerve palsies, gait disturbance.
⭐ The triad of morning headache, vomiting, and ataxia is highly suggestive of a posterior fossa tumor.
Tumor Types - Rogues' Gallery
- Most common solid tumors in children. Location is key: ~60% are infratentorial (posterior fossa).
| Tumor Type | Key Features & Histology | Location |
|---|---|---|
| Pilocytic Astrocytoma (Grade I) | - Most common pediatric brain tumor. - Biphasic pattern: dense fibrillary areas + loose microcystic areas. - Rosenthal fibers (eosinophilic corkscrew bodies). - GFAP positive. | Cerebellum |
| Medulloblastoma (Grade IV) | - 2nd most common; most common malignant type. - Small, round, blue cells. - Homer-Wright rosettes. - Highly radiosensitive. | Cerebellum (Vermis) |
| Ependymoma | - Arises from ependymal cells lining ventricles. - Perivascular pseudorosettes. - Often presents with hydrocephalus. | 4th Ventricle |
| Craniopharyngioma | - From Rathke's pouch remnants. - Bimodal age distribution (5-14 yrs & 50-74 yrs). - "Wet keratin" & dystrophic calcification. - Cholesterol-rich, "machine oil" fluid. | Suprasellar |
⭐ High-Yield: Medulloblastoma is the most common malignant brain tumor of the posterior fossa in children and has a tendency to disseminate via CSF (drop metastases).
Diagnosis & Management - The Battle Plan
- Imaging: MRI with gadolinium contrast is the gold standard for diagnosis & surgical planning.
- Histopathology: Biopsy or surgical resection provides definitive diagnosis & grading.
- Supportive Care: Dexamethasone to ↓ vasogenic edema; manage hydrocephalus with VP shunt.
⭐ High-Yield Fact: Radiotherapy is typically avoided or delayed in children < 3 years of age to prevent severe, long-term neurocognitive deficits. Chemotherapy is often used as a bridge (neoadjuvant therapy) in these young patients.
High‑Yield Points - ⚡ Biggest Takeaways
- Most common solid tumors in children; second most common malignancy after leukemia.
- Majority are infratentorial (posterior fossa), unlike in adults.
- Pilocytic astrocytoma is the most common type; often low-grade.
- Medulloblastoma is the most common malignant tumor, located in the cerebellum.
- Classic triad of ↑ Intracranial Pressure: morning headache, vomiting, and papilledema.
- Craniopharyngiomas: Supratentorial tumors from Rathke's pouch remnants causing visual defects.
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