Imaging of brain tumors in children: the basics—a narrative review

Abstract

Childhood CNS cancer was also the top reason for cancer mortality in children in 2009 (2).Unlike neoplasms in other locations, primary brain tumors are not staged, but categorized according to the World Health Organization (WHO) 2016 Classification, which relies on molecular parameters in addition to histology to define their entities (3). Our goal is to offer an overview of these tumors, describing the imaging characteristics of the most common primary brain tumors in children based on the WHO classification update. We present the following article in accordance with the Narrative Review reporting checklist (http://dx.doi.

Novel insights on genetics and epigenetics as clinical targets for paediatric astrocytoma

“…Even though the histopathologic features of high-grade gliomas (HGG) are similar in children and adults, the molecular paradigms underlying these tumours differ significantly leading to different management regimens in children as compared to adults. [46][47][48] According to the recent classification changes, highgrade tumours include DMG, H3 K27-altered, diffuse hemispheric glioma, H3 G34-mutant, diffuse hemispheric glioma and H3 G34-mutant infant-type hemispheric glioma. However, neurooncologists and neuropathologists are still advocating for more clarification on the classification of paediatric tumours.…”

“…Histologically, these tumours are diffusely infiltrative, with irregular heterogeneous textures and ill‐defined boundaries. Other visual markers include multinucleated cells, sporadic nuclei, satellite lesions, neovascularisation and calcific components (mostly in secondary GBM) 46 …”

“…DIPG (now regarded as diffuse hemispheric glioma, H3.3G34 mutant) on the other hand have a lower incidence of .05–.06 per 100 000 with a median age of diagnosis between 6 and 9 years old. DIPG is primarily found within the pons, brain stem and spinal cord and the most common clinical symptoms include motor deficits, facial weakness, dysarthria, diplopia and conjugate gaze palsy as a result of dysfunctional pontine structures 46 . Also in the latest classification two new subtypes have been defined for DIPGs with H3 wild‐type with loss of H3K27 trimethylation such as DMG, EZH inhibitory protein ( EZHIP ) overexpressed and DMG, EGFR mutant.…”

Imaging Guidelines and Recommendations for Diagnosis, Surveillance, and Management of Pediatric CNS and Spinal Tumors

“…14 Enhancement plays an important role for tumor follow-up (f/u) for the lesions that showed enhancement at baseline imaging, to map the tumor extent or recurrence on f/u imaging (e.g., PA) and also for nonenhancing lesions at baseline that show abnormal postcontrast enhancement on f/u suggesting progression or change in lesion grade (e.g., World Health Organization [WHO] grade I diffuse astrocytoma MYB or MYBL1 altered). 14 Postcontrast imaging can also help to assess tumor response as LGG show significantly reduced enhancement after treatment with MEK inhibitors or BRAF inhibitors; however, this should be weighed with tumor size measurement on T2W/FLAIR imaging. 9 DWI with ADC maps is one of the most important sequences for pediatric CNS tumor grading.…”

“…However, postcontrast enhancement is particularly important in some metastasizing low-grade tumors (e.g., 5–10% of PA can metastasize) that only show enhancement and this can be the only feature on imaging to pick up smaller lesions or leptomeningeal spread. 14 Enhancement plays an important role for tumor follow-up (f/u) for the lesions that showed enhancement at baseline imaging, to map the tumor extent or recurrence on f/u imaging (e.g., PA) and also for nonenhancing lesions at baseline that show abnormal postcontrast enhancement on f/u suggesting progression or change in lesion grade (e.g., World Health Organization [WHO] grade I diffuse astrocytoma MYB or MYBL1 altered ). 14 Postcontrast imaging can also help to assess tumor response as LGG show significantly reduced enhancement after treatment with MEK inhibitors or BRAF inhibitors; however, this should be weighed with tumor size measurement on T2W/FLAIR imaging.…”