Pediatric and Adult Low-Grade Gliomas: Where Do the Differences Lie?

Ladina Greuter,Raphael Guzman,Jehuda Soleman

doi:10.3390/children8111075

Abstract

Two thirds of pediatric gliomas are classified as low-grade (LGG), while in adults only around 20% of gliomas are low-grade. However, these tumors do not only differ in their incidence but also in their location, behavior and, subsequently, treatment. Pediatric LGG constitute 65% of pilocytic astrocytomas, while in adults the most commonly found histology is diffuse low-grade glioma (WHO II), which mostly occurs in eloquent regions of the brain, while its pediatric counterpart is frequently found in the infratentorial compartment. The different tumor locations require different skillsets from neurosurgeons. In adult LGG, a common practice is awake surgery, which is rarely performed on children. On the other hand, pediatric neurosurgeons are more commonly confronted with infratentorial tumors causing hydrocephalus, which more often require endoscopic or shunt procedures to restore the cerebrospinal fluid flow. In adult and pediatric LGG surgery, gross total excision is the primary treatment strategy. Only tumor recurrences or progression warrant adjuvant therapy with either chemo- or radiotherapy. In pediatric LGG, MEK inhibitors have shown promising initial results in treating recurrent LGG and several ongoing trials are investigating their role and safety. Moreover, predisposition syndromes, such as neurofibromatosis or tuberous sclerosis complex, can increase the risk of developing LGG in children, while in adults, usually no tumor growth in these syndromes is observed. In this review, we discuss and compare the differences between pediatric and adult LGG, emphasizing that pediatric LGG should not be approached and managed in the same way as adult LCG.

Highlights

Brain tumors are the most common solid cancer in children, with an incidence of 5.7 per 100,000 [1]
Pediatric LGGs are defined as astrocytoma World Health Organization (WHO) grade I and II, and include several different pathological subtypes, such pilomyxoid astrocytomas, oligodendrogliomas, gangliogliomas or supendemal giant cell astrocytomas [3,4,5]
Most pLGGs occur in the cerebellum, while in adults, they mostly occur in the supratentorial compartment [4]

Summary

Introduction

Brain tumors are the most common solid cancer in children, with an incidence of 5.7 per 100,000 [1]. TThhee TTSSCCnneeggaattiivveellyyrreegguullaatteess tthheemmTTOORRppaatthhwwaayy, resulting in typical subependymal ggiiaanntt cceellll aassttrrooccyyttoommaa ((SSEEGGAA)) iinn 2200%% off all patients, and only a small number of reports ooff SSEEGGAA wwiitthhoouutt tthhee cclliinniicaal features of TSC exist (Figure 2) [31,32] These tumors mostly ooccccuurr iinn childdrreenn and young adults and are unlikely to occur in adulthood [30]. For both NF-1 associated OPGs and TSC-associated SEGAs, a diagnosis can be made based on typical MRI features, and a biopsy is not obligatory to confirm histopathological diagnosis before starting medical therapy [35] This stands in contrast to the usual treatment paradigm, which requires the performance of a biopsy before starting therapy for any other presumed LGG, especially in adults. In children, posterior fossa syndrome, including cerebellar mutism occurs in approximately a third of patients undergoing infratentorial tumor resection, while this is an extremely rare complication after posterior fossa surgery in adults [41]. This most probably due to differences in histology and tumor biology

Adjuvant Therapy

Molecular Genomics and Targeted Therapies

Malignant Transformation

Spontaneous Regression in pLGG

Findings

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