Pediatric low grade glioma

Epidemiology
Most common childhood brain tumor (~1000 per year in US)

Risk factors
NF1 (associated with optic glioma, cafe-au-lait spots)
Tuberous sclerosis (cortical tubers, subependymal giant cell astrocytoma, mental retardation)
Prior XRT

Juvenile pilocytic astrocytoma
WHO Grade 1
Most common glioma in children
Frequently seen in cerebellum, optic tract
Path: Rosenthal fibers; pilomyxoid variant may be more aggressive
Imaging: T2-bright cystic lesion with mural nodule
Observation is recommended after complete resection and frequently after subtotal resection in non-eloquent area

Diffuse/fibrillary astrocytoma
WHO Grade II
Brainstem, cerebral hemispheres
Associated with p53 mutation, LOH @ chromosome 17
May be observed after complete resection; RT for progressive tumor/subtotal or unresectable disease
Chemotherapy may stabilize disease in young children and allow deferral of RT

Optic glioma
Often indolent
Lesions in the posterior part of the pathway (hypothalamus and beyond into optic radiation and occipital cortex) may behave more aggressively
Surgery may be recommended if visual loss already exists and tumor is growing
Patients with intact vision usually given chemo and RT