Pilocytic astrocytoma

Case contributed by Frank Gaillard


Headache and cranial nerve dysfunction.

Patient Data

Age: 8 years
Gender: Male

CT brain


There is a large partially cystic mass in the right cerebellar hemisphere. The solid component minimally enhances with a focal region demonstrating more prominent ring enhancement. The fourth ventricle is effaced, and the lateral ventricles are enlarged. There is also marked mass effect on the brainstem with the prepontine and perimesencephalic cisterns obliterated. 

MRI brain


Redemonstration of a large partially cystic mass, with its epicenter in the right cerebellar hemisphere, displacing and effacing the fourth ventricle, resulting in hydrocephalus. 

The mass has a solid component, which is nodular, and slightly hypointense on T1 compared to the cerebellum, and hyperintense on T2. It demonstrates bright contrast enhancement. 

Case Discussion

A cystic mass with mural enhancement in a child arising from the cerebellar hemisphere is usually a pilocytic astrocytoma. This patient went on to have a craniotomy and resection which confirmed the diagnosis. 

Case courtesy of Bob Cook, MD. Western Memorial Regional Hospital Corner Brook, Newfoundland.

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