Supratentorial malignant gliomas continue to be 1 of the most difficult types of brain tumors to treat in children. The authors present a comprehensive review of the basic principles and practices underlying the causes, diagnosis, treatment, and outcomes of supratentorial malignant gliomas in children. The authors also present updated therapeutic and molecular research advancements in these childhood tumors.
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• Molecular classification of malignant gliomas is examined.
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• Key differences between adult and pediatric malignant gliomas are discussed.
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• Tumor grade and gross total resection remain the most important prognostic indicators for a favorable outcome.
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• Children less than 3 years of age have improved outcomes compared to children greater than 3 years of age.
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• Survival remains poor, and targeted therapies have had minimal results; however, new clinical trials are currently being investigated.
Historical note and terminology
Brain tumor classification began in the 1920s. The proposed classification system for gliomas was based on the idea that gliomas originated from central nervous system cells arrested at various stages of development (03). Recognizing that brain tumors contained heterogeneous cell populations, gliomas were classified on the basis of the morphological appearance and presumed histogenesis of the predominant cell type. Most of the classification schemes have been constructed to various degrees around the conceptual framework introduced by Bailey and Cushing (84; 43). Other classifications have proposed that glial cells become progressively more anaplastic, rather than undergo a single neoplastic transformation to malignant glioma (87). This concept has led to the proposal to simplify brain tumor classification in order to reflect the degree of anaplasia that is present by grading the tumors from grade I (benign) to grade IV (malignant). However, with advancements in tumor biology genetics, it is now known that histopathology alone cannot provide prognostic value to the diagnosis. As a result, in 2016, an international collaboration of renowned scientists and clinicians revised the current World Health Organization classifications by including molecular parameters (53).
Since the 2016 update, the World Health Organization recognizes the following entities as supratentorial malignant gliomas: grade III anaplastic astrocytoma, IDH-mutant, anaplastic oligodendroglioma, IDH-mutant and 1p/19q-codeleted (uncommon amongst pediatric patients), anaplastic pleomorphic xanthoastrocytoma and grade IV glioblastoma, IDH-wild-type (uncommon amongst pediatric patients), glioblastoma, and IDH-mutant. The diagnosis of anaplastic oligoastrocytoma has been eliminated, as tumors with histological features of both astrocytoma and oligodendroglioma components are now classified as either astrocytoma or oligodendroglioma based on the absence or presence of chromosomes 1p/19q codeletion, respectively, from genetic testing. Oligoastrocytomas have been assigned a NOS status if molecular testing is not available (53). An account of the historical evolution of glioma terminology has been previously provided in much greater detail (103).