Pilocytic astrocytoma

Case contributed by Ryan Thibodeau
Diagnosis certain

Presentation

Hemiplegia. Suspected right-sided hemiplegia with weakness and spasticity. Symptomatic for 6 months.

Patient Data

Age: 3 years
Gender: Male
mri

There is a large cystic lesion within the brain parenchyma located at the left cerebral hemisphere at the frontoparietal junction. The internal cystic components demonstrate lack of suppression on the FLAIR sequence. There are areas of minimal peripheral nodularity with enhancement. The dominant area of nodularity is identified along the posterior superior aspect of the cystic lesion where there is a thickened region of enhancement. There are smaller additional foci of enhancement anteriorly. Foci of susceptibility are seen along the periphery of the cystic lesion, particularly inferiorly, which may be related to hemosiderin staining or peripheral mineralization. There is marked surrounding vasogenic edema contributing to regional mass effect effacing the left cerebral sulci as well as severe effacement of the left lateral ventricle with associated rightward midline shift and effacement of the basal cisterns. There is rightward subfalcine, left uncal, and transtentorial herniation.

The right lateral ventricle body and bilateral temporal horns are enlarged compatible with transependymal flow of CSF. There is corresponding inversion of the bilateral optic disc, presumably related to papilledema from increased intracranial pressure.

Case Discussion

This is a pilocytic astrocytoma with anaplasia.

The patient underwent resection and fenestration of the left frontoparietal tumor via a left parietal craniotomy. The gross pathologic specimen revealed tan-pink soft tissue fragments. Histopathologically, the tumor was noted to be a glial neoplasm with moderately to markedly increased cellularity and multifocal microscopic infiltrative growth into adjacent cortex. The lesional cells were ovoid or round, displaying nuclear hyperchromasia, increased nuclear to cytoplasmic ratio, occasional multinucleation and identifiable mitoses, with up to 6 mitoses in 10 high power fields. Rare apoptotic bodies and microcalcifications were present. Rosenthal fibers and eosinophilic granular bodies were not seen. On immunohistochemistry, the lesional cells were positive for GFAP, Olig2 (strong diffuse), vimentin, SOX10, synaptophysin and CD34 (weak and multifocal). ATRX was positive/retained and a subset of tumor cells were positive for p53 with moderate to strong staining intensity. Ki-67 proliferation index was 7.3% (51/699). The neurofilament-positive neurites were multifocally seen in the tumor, indicating microscopic infiltration.

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