Supratentorial Intracranial Tumors In Children

Introduction And Epidemiology

Supratentorial tumors account for approximately 40.9% of primary pediatric central nervous system (CNS) tumors.
Exhibit distinct age-related predilection.
Predominate during first year of life (choroid plexus tumors, germ cell tumors).
Predominate again after 10 years of age (diffuse astrocytomas, pituitary/craniopharyngeal tumors).

Optic Pathway Gliomas: Constitute 5% of pediatric CNS tumors. Account for 15% of tumors in patients with neurofibromatosis type 1 (NF-1). Histologically, 90% are low-grade astrocytomas.
Pilomyxoid Astrocytoma: Occurs primarily in hypothalamic/optic chiasmic region in infants. Carries high risk of cerebrospinal spread.
Diffuse Astrocytomas: Predilect supratentorial locations. Evolution to malignant astrocytoma linked to cumulative molecular abnormalities (p53 mutation, platelet-derived growth factor receptor-alpha overexpression).
High-Grade Gliomas: Include anaplastic astrocytoma and glioblastoma multiforme. Harbor characteristic genetic alterations: mutations in histone H3.3, H3.1, p53, BRAF, and amplification of oncogenes (PDGFRA).

Arise in suprasellar region; account for 6-9% of pediatric CNS tumors.
Adamantinomatous subtype common in children; exclusively harbors CTNNB1 mutations.
Slow-growing, benign lesions engulfing vital anatomic structures.
Neuroimaging demonstrates solid and cystic components with calcifications.

Arise predominantly in midline structures (pineal and suprasellar regions).
Account for 3-5% of pediatric CNS tumors; peak incidence 10-12 years.
Include pure germinomas (highly curable, >90% survival) and nongerminomatous GCTs (70-80% survival).
Characterized by secretion of tumor markers: alpha-fetoprotein (AFP) and beta-human chorionic gonadotropin (b-hCG).

Most common CNS tumor in infants <1 year.
Predominantly occur supratentorially in lateral ventricles.
Choroid plexus papilloma (WHO grade I) curable with complete resection.
Choroid plexus carcinoma (WHO grade III) malignant, seeds cerebrospinal fluid (CSF).
Strongly associated with Li-Fraumeni syndrome (p53 mutation).

Supratentorial PNET: Composed of undifferentiated neuroepithelial cells; requires highly dose-intense therapy.
Atypical Teratoid/Rhabdoid Tumor (AT/RT): Aggressive malignancy of infancy. Characterized by loss of chromosome 22q11.2 and INI1/SMARCB1 mutation.

Visual Disturbances: Decreased visual acuity, visual field defects, Marcus Gunn pupil, nystagmus.
Neuroendocrine Deficits: Precede neuroophthalmologic dysfunction by average 1.9 years. Include diabetes insipidus, delayed/precocious puberty, hypothyroidism, galactorrhea, abnormal linear growth.

Parinaud Syndrome: Paresis of upward gaze, pseudo-Argyll Robertson pupil (reactive to accommodation, not light), convergence/retraction nystagmus, eyelid retraction.

Magnetic resonance imaging (MRI) with and without gadolinium remains diagnostic standard.
Delineates complex cystic/solid structures and blood-brain barrier breakdown.
Computed tomography (CT) identifies focal calcifications typical of craniopharyngiomas or oligodendrogliomas.

Formal ophthalmologic evaluation maps visual field deficits and acuity.
Comprehensive endocrine panel required for midline/suprasellar tumors.
Serum and CSF tumor markers (AFP, b-hCG) diagnostic for secreting germ cell tumors.
Lumbar puncture for CSF cytology contraindicated with obstructive hydrocephalus or supratentorial midline shift (herniation risk).

Primary goal remains gross total resection with preservation of neurologic function.
Completely resected low-grade supratentorial astrocytomas yield 76-100% 5-year survival.
Endoscopic third ventriculostomy useful for reducing intracranial pressure prior to definitive resection.

Delayed or avoided in children <3 years due to severe late effects (microcephaly, cognitive impairment, panhypopituitarism).
Proton-beam radiotherapy increasingly utilized to conform radiation volume and spare adjacent normal tissue.

Adjuvant chemotherapy utilized to shrink residual tumor or avoid radiation in infants.
BRAF Inhibitors: Trametinib or dabrafenib effectively stabilize/shrink BRAF-mutated low-grade gliomas.
mTOR Inhibitors: Everolimus utilized for tuberous sclerosis-associated subependymal giant cell astrocytomas.