Pilocytic astrocytoma

Case contributed by Bruno Di Muzio
Diagnosis certain


Pregnant lady with increasing headaches.

Patient Data

Age: 25 years
Gender: Female

MRI Brain


There is a 4 cm T2 hyperintense midline cerebellar mass which distorts the fourth ventricle and medulla without significant hydrocephalus but resulting in crowding of foramen magnum with mild cerebellar tonsillar herniation. 

Case Discussion

The patient went on to have a resection. 


Sections show a variably cellular tumor with a prominent microcystic architecture. Tumor cells
demonstrate elongated oval nuclei with inconspicuous nucleoli set within a fibrillary stroma. Frequent Rosenthal fibers and eosinophilic granular bodies are seen. There are focal aggregates of thin-walled, hyalinised blood vessels with the adjacent parenchyma containing hemosiderin deposition. No mitoses, necrosis or microvascular proliferation are identified.


  • GFAP: Positive
  • IDH-l R132H: Negative (non-mutated)
  • ATRX: Positive (non-mutated)
  • p53: Positive
  • BRAF V60oE: Negative
  • Topoisomerase labeling index: Approximately 1-2%.

FINAL DIAGNOSIS: Pilocytic astrocytoma (WHO Grade I).

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