High-Grade Gliomas in Early Adulthood: A Case-Based Review of Current Molecular Diagnostic Considerations

Abstract High-grade gliomas in early adulthood (between the ages of 20 and 40 years) have a wide differential diagnosis that includes entities from childhood and late adulthood. These gliomas are increasingly defined by their molecular signatures, requiring a molecular-based workup that is informed by morphology and anatomy. Here we present four cases with four different diagnoses, some rare and some common, presenting with new brain lesions. This diagnostic process is informed by the 2016 World Health Organization guidelines, c-IMPACT Now updates, and the clinico-pathologic features shown by these high-grade tumors. Particularly, we focus on practical diagnostic decisions that may need to be made with limited tissue and/or limited on-site molecular resources.