Abstract
Diffuse midline glioma (DMG), H3 K27M-altered, is a tumor with a poor prognosis mainly found in children. An adolescent patient presented with thalamic hemorrhage, which initially could not be diagnosed as DMG by pathological analysis. A neoplasm in the lateral ventricle close to the previous thalamic hemorrhagic lesion was detected 12 months after the hemorrhage. Thus, endoscopic resection was performed, and a diagnosis was made. Gene expression profiling demonstrated mutation in genes, such as H3F3A and FGFR1. FGFR1 mutation was associated with intratumoral hemorrhage in low-grade gliomas and contributed to longer survival than wild-type FGFR1 in DMG H3K27M. Our findings suggest that patients with DMG, H3 K27-altered, with FGFR1 mutation may be predisposed to intratumoral hemorrhaging and/or have a longer survival time than patients without FGFR1 mutation.