Diffuse Midline Glioma H3 K27-Mutant in an Adult: A Rare Case

Abstract

Diffuse midline glioma, H3K27M-mutant, WHO grade IV (DMGM), is a newly established entity in the 2016 WHO classification. It is uncommon and the median age of diagnosis is 5-11 years. Due to their rarity in adults, their recognition can be challenging even though the histopathology and phenotypes of adult and pediatric cases are similar. We report a case of a middle-aged female who presented with seizures and persistent headache, where imaging revealed an enhancing suprasellar mass involving the hypothalamus and fornix and she was diagnosed with H3K27M-mutant diffuse midline glioma. DMGM is extremely rare in adults and therefore, more cases need to be reported to enable their recognize among neuropathologists. Also, this report suggests a needed emphasis on obtaining molecular studies whenever possible if there is a suspicion of H3K27M-mutant DMGM, given that they are extremely aggressive and have poor clinical outcomes in most cases. The case was presented at College of American Pathologists (CAP) annual conference in Chicago (October 2018) and the abstract was published in Archives as an online supplement only. Keywords: Glioma; Suprasellar; Hypothalamus; Fornix; Midbrain; Thalamus