Pediatric Low-Grade Gliomas

Abstract

Brain tumors constitute the largest source of oncologic mortality in children and low-grade gliomas are among most common pediatric central nervous system tumors. Pediatric low-grade gliomas differ from their counterparts in the adult population in their histopathology, genetics, and standard of care. Over the past decade, an increasingly detailed understanding of the molecular and genetic characteristics of pediatric brain tumors led to tailored therapy directed by integrated phenotypic and genotypic parameters and the availability of an increasing array of molecular-directed therapies. Advances in neuroimaging, conformal radiation therapy, and conventional chemotherapy further improved treatment outcomes. This article reviews the current classification of pediatric low-grade gliomas, their histopathologic and radiographic features, state-of-the-art surgical and adjuvant therapies, and emerging therapies currently under study in clinical trials.

Keywords: BRAF mutation; diffuse astrocytoma; molecularly-targeted therapy; neuroepithelial tumor; pediatric low-grade glioma; pilocytic astrocytoma; pleomorphic xanthoastrocytoma; subependymal giant cell astrocytoma.

Figure 1

Left frontal diffuse astrocytoma, WHO 2: (A) sagittal T2 Fluid-attenuated inversion recovery (FLAIR) and (B) axial T2 FLAIR sequences demonstrate a diffusely infiltrating, hyperintense lesion in the left superior frontal gyrus.

Figure 2

Juvenile pilocytic astrocytoma, WHO 1: (A) sagittal T2 FLAIR with contrast and (B) axial T1 with contrast demonstrate a heterogeneous, multicystic, avidly enhancing mass arising from the left cerebellar hemisphere.

Figure 3

Giant ganglioglioma with extensive chondroid metaplasia, WHO I, arising from the left frontal lobe demonstrates multinodular architecture and sparse, heterogeneous contrast enhancement on these (A) sagittal and (B) axial T1 MPRAGE contrast-enhanced images.

Figure 4

Desmoplastic infantile ganglioglioma, WHO I: (A) axial T1 MPRAGE contrast enhanced and (B) axial T2 images demonstrate a large right frontoparietal mass with a large cystic component and a superficial enhancing nodule with adjacent perilesional parenchymal edema.

Figure 5

Dysembryoplastic neuroepithelial tumor, WHO I: (A) axial T1 MPRAGE with contrast, (B) axial T2 FLAIR with contrast, and (C) axial T2 without contrast demonstrate a small cystic lesion abutting the central sulcus in the left hemisphere. There is a small nodule and rim of enhancement at the medial aspect of the tumor.