Exophytic brainstem glioma

Case contributed by Dr Ahmed Abdrabou


Recurrent attacks of headache, vomiting and blurring of vision.

Patient Data

Age: 14 years old
Gender: Male

Large ill defined intra-axial space occupying lesion occupying the posterior fossa, centered on the 4th ventricle and inseparable from the brainstem. No significant enhancement on post contrast study. the rest of the 4th ventricle is compressed to the right side and there is supratentorial hydrocephalic changes and right frontal area of encephalomalacia from previous traumatic hemorrhage.


The mass returns hypointense signal on T1, hyperintense signal on T2 and FLAIR, bright signal on DWI and ADC denoting facilitated diffusion. No significant post contrast enhancement. It is ill defined and no line of cleavage between the mass and the posterior pons. MRS reveals reduced NAA, elevated Cho and in some areas there is elevated lactate as well denoting degeneration.

Case Discussion

Dorsal (exophytic) brainstem glioma is a subtype of glioma that arise from the dorsal aspect of brainstem and extends posteriorly.

Differential diagnosis includes medulloblastoma, ependymoma and pilocytic astrocytoma.

Biopsy from this lesion revealed WHO grade I astrocytoma.

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Case information

rID: 35712
Published: 18th Apr 2015
Last edited: 15th Dec 2015
Inclusion in quiz mode: Included

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