All are true about pilocytic astrocytoma, EXCEPT:

Pilocytic astrocytomas (grade I/IV) are distinguished from the other types by their pathologic appearance and relatively benign behavior. They typically occur in children and young adults, and are usually located in the cerebellum. On macroscopic examination, a pilocytic astrocytoma is often cystic; if solid, it may be well circumscribed or, less frequently, infiltrative. Ref: Robbins 8th edition Chapter 28.