Pilocytic astrocytoma

Case contributed by Assoc Prof Frank Gaillard



Patient Data

Age: 45 years
Gender: Male

Centered within left parietal white matter are 2 closely adjacent cystic regions that demonstrate incomplete suppression of their contents on FLAIR, with a thin T2 hypointense wall containing some susceptibility artefact. Following contrast administration there a few foci of linear enhancement at the margins, plus a punctate enhancing focus immediately inferior. Lesions are surrounded by white matter T2 hyperintensity that tracks inferiorly to abut the lateral wall of the left lateral ventricle trigone, but does not extend into the subcortical U fibers or involve overlying cortex.

There is no cerebral blood volume (CBV) increase. MR spectroscopy in voxels covering with the non-enhancing portions wall demonstrates mild choline elevation in NAA reduction with large lipid lactate peak. Spectroscopy performed within the white matter abnormality only demonstrate a lipid lactate peak with no choline elevation.

Elsewhere in the brain, incidental note is made of a left superior frontal gyrus developmental venous anomaly. There is no hydrocephalus.

Case Discussion

The patient went on to have a biopsy.


Sections of the white matter show increased cellularity. There are scattered bipolar astrocytes. Very focal fascicular arrangement is noted. These cells have elongated and hyperchromatic nuclei. There are other single cells with moderate nuclear enlargement and hyperchromasia. Scattered Rosenthal fibers are also present. 

Final diagnosis: pilocytic astrocytoma

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