Paediatrics: Central nervous system tumours (1)

Central nervous system tumours (1)

Brain tumours are the most common solid tumours, accounting for 25% of all childhood malignancies.

·  Involvement of the multidisciplinary team is central to management of CNS tumours.

·  The presenting features vary and may delay the diagnosis. For every childhood brain tumour, there are 75000 children with migraine!

Initial management

Diagnostic imaging

·  CT is quick and available. It provides essential information for emergency management of hydrocephalus.

·  MRI gives better tumour definition. Combine with spinal imaging for staging of disease.

Raised intracranial pressure

This requires prompt treatment:

·  Referral and transfer to a paediatric neurosurgical unit.

·  Control tumour swelling with high dose steroids (usually dexamethasone).

·  CSF drainage: initial surgery may involve CSF diversion only, biopsy, or complete resection, depending on location and likely diagnosis.

Low grade glioma (grade I, 45% CNS tumours)

·  Most are pilocytic astrocytoma.

·  Cerebellum and optic pathway are most common sites.

·  Outcome depends on site. Posterior fossa lesions can be cured with surgery alone, whereas optic pathway tumours are relatively inaccessible and morbidity is high.

Neurofibromatosis type 1 (NF1)

·  50% of optic pathway low grade gliomas.

·  Visual outcome better.

Radiotherapy contraindicated - increased risk of second tumours.

High grade glioma (grade III/IV, 10% CNS tumours)

·Predominantly occur in older children and teenagers.

·Supratentorial sites predominate.

·Difficult to manage since complete resection, essential for good outcome, is difficult to achieve.

·Rarely cured. Treatment usually includes radiotherapy, with the addition of temozolamide or other agents in the context of clinical trials

Diffuse brainstem glioma

·Glioma in the region of the pons, usually high-grade and inoperable.

·Radiotherapy is the mainstay of treatment.

·Median survival <1yr.

Primitive neuroectodermal tumours (PNETs, 25% CNS tumours)

·Most common malignant brain tumours of childhood.

·Majority occur in the cerebellum (medulloblastoma).

·Peak incidence is <5yrs.

·Tumour metastases (mainly via the CSF) in 10–15%.

·70% of localized cases can be cured, but expect significant long-term morbidity from radiotherapy.

Treatment

Treatment includes excision and craniospinal radiotherapy. Additional chemotherapy carries a survival advantage, allowing reduction in drug dose and/or field of radiotherapy, particularly in younger patients. Chemotherapy regimens include alkylating agents (e.g., Lomustine (CCNU), cyclophosphamide), platinum drugs (cisplatin, carboplatin), and vincristine. These are usually given after radiotherapy.