Low-grade Gliomas

Chapter 11 - Classification and Treatment of Paediatric Brain Tumours

General Aspects

LGGs are slow-growing tumours, with a relatively benign histology. They include pilocytic astrocytoma, diffuse astrocytoma, ganglioglioma, glio-neuronal tumours and mixed neuronal-glial tumours.

Average age at diagnosis ranges from 6 to 9 years. Spine metastases in LGG are rare, affecting 5% of children.

Optic Pathway Glioma

The term “optic pathway gliomas” (OPGs) indicates pilocytic astrocytomas arising in the optic nerves, chiasm and hypothalamus. They account for 3%–5% of paediatric intracranial tumours.

Children with Type 1 neurofibromatosis (NF1) have an approximately 20% risk of developing an optic glioma. Patients with NF1 have a less aggressive clinical course than children without NF1.

Treatment

Gross total excision is the goal. This is possible in the majority of hemispheric tumours, but in only a minority of diencephalic tumours. Carboplatin-containing ChT and/or RT are reserved for recurrent or progressive tumours and/or symptomatic patients. Treatment decisions are based largely on the tumour location and the patient’s age at diagnosis.

The most frequent genomic alteration in paediatric LGGs are KIAA-BRAF fusion genes or BRAF V600 mutations, which activate the mitogen-activated Protein kinase (MAPK) pathway.

Vemurafenib and dabrafenib are competitive small molecules that bind and inhibit the ATP-binding domain of mutant BRAF V600E.

Revision Questions

  1. What can you say about the histology of LGGs?
  2. Which syndrome is often associated with OPG?
  3. What is the main Prognostic factor in children with LGG?

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Last update: 18 September 2017