Case discussion
01Clinical context
A paediatric patient presented with new-onset seizures, gait disturbance and speech difficulty; contrast-enhanced MRI was requested to evaluate for an intracranial space-occupying lesion.
02Key imaging findings
There is a large intra-axial infiltrative expansile mass centred within the pons (approximately 6.1 × 3.0 × 4.0 cm), predominantly T2/FLAIR hyperintense and T1 hypointense, with internal foci of diffusion restriction and no significant post-contrast enhancement. It effaces the prepontine cistern, extends into the left cerebellopontine angle and near-completely encases the basilar artery, whose flow void is preserved. Severe fourth-ventricular compression produces moderate active obstructive hydrocephalus with bilateral transependymal CSF seepage, plus perioptic CSF sleeve dilatation and mildly low-lying cerebellar tonsils without frank herniation. The location and non-enhancing infiltrative phenotype are highly concerning for a diffuse midline glioma of the pons (DIPG phenotype).
03Teaching point
A diffusely expansile, T2-hyperintense, largely non-enhancing pontine mass in a child is the classic imaging phenotype of diffuse midline glioma (DIPG); lack of enhancement does not imply low grade. Look for basilar artery encasement with preserved flow void, effacement of the prepontine cistern, and secondary fourth-ventricular obstruction with transependymal seepage as markers of active hydrocephalus and raised ICP. Definitive classification, including H3 K27 alteration status, requires tissue/molecular characterisation when clinically undertaken.
Shown for education. De-identified — no identifiable patient data. A radiology report is a specialist opinion and must be read with the full clinical context by the treating physician.