RESUMO
BACKGROUND: Disseminated diffuse midline glioma (DMG) is a devastating diagnosis. Molecular subtyping has increased our understanding of this tumor. CASE: Here, we report the case of an 8-year-old girl who presented with symptoms of brainstem dysfunction and was found to have disseminated DMG with lesions in the pons, thalamus and bilateral temporal lobes. Molecular subtyping of the temporal lobe tumor tissue was consistent with H3 K27me3 loss and EZHIP overexpression, falling under the newly designated "H3 K27-altered" AQ5WHO subtype of DMG. Pathology from biopsy of the orbital lesion showed poorly differentiated rhabdoid-like disseminated tumor cells. The patient went on to develop lesions in the peritoneum, infratemporal fossa, and along the lumbosacral nerve roots. CONCLUSION: This unique case illustrates the aggressive behavior of H3 K27-altered tumors and their potential to metastasize.