A 4-year-old male presented with rapid-onset cranial nerve palsy and ataxia. Brain magnetic resonance imaging (MRI) revealed a pontine mass lesion with discordant conventional and advanced imaging. A stereotactic core biopsy revealed glioblastoma with immunostaining suggestive of histone H3K27M and TP53 mutation, consistent with diffuse intrinsic pontine glioma. MRI 3 months after radiotherapy revealed extensive new leptomeningeal metastatic disease involving both the supra- and infratentorial brain, as well as the imaged portion of the spine. Tissue procured at the time of needle biopsy has undergone striking in vivo expansion as an orthotopic xenograft.
Keywords: H3K27M; hypofractionated radiotherapy; leptomeningeal metastasis; pontine glioma; stereotactic biopsy; xenograft.
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