Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Pilocytic astrocytoma ?
    ### Response:
    Pilocytic astrocytoma is an often benign, slow-growing tumor of the brain or spinal cord. The tumor may be in the form of a cyst and usually does not spread to nearby tissues. Symptoms vary depending upon the size and location of the tumor. Most symptoms result from increased pressure on the brain and include headaches, nausea, vomiting, balance problems, and vision abnormalities.
    