IDH-mutant brainstem gliomas in adolescent and young adult patients: Report of three cases and review of the literature

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Chang, Ellen K., Smith‐Cohn, Matthew A., Tamrazi, Benita, Ji, Jianling, Krieger, Mark, Holdhoff, Matthias, Eberhart, Charles G., Margol, Ashley S., Cotter, Jennifer A.


In contrast to adult gliomas, isocitrate dehydrogenase (IDH) mutations are rare in pediatric and adolescent gliomas. In a recent series of over 1000 pediatric low grade gliomas (LGG), the IDH1 R132H mutation was found in only 0.8% of studied cases, with those identified occurring in older children/adolescents (median 15.7 years) and exclusively in the cerebral hemispheres (1). Other studies show a slightly higher incidence (up to 16%) of IDH mutations in pediatric high grade gliomas (HGG), with comparable age range and exclusivity to hemispheric locations (2). IDH-mutant gliomas arising in the brainstem are exceedingly rare in both the adult and pediatric population. Infratentorial location is uncommon in diffuse gliomas, with 5% or less occurring in the brainstem, cerebellum, or spinal cord, and IDH mutations in the infratentorial compartment appear to be rare (7%) (3–5). Brainstem gliomas are very rare in adults, but approximately 10% of pediatric CNS tumors occur in this location, with diffuse midline glioma, K27M-mutant representing most cases.