Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Meningioma ?
    ### Response:
    Meningiomas originate in the meninges, the membranes that surround the brain and spinal cord. Most meningiomas are benign, though a minority of meningiomas can be classified as atypical or malignant. Though rare, malignant meningiomas can be highly aggressive.
    