Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) idiopathic inflammatory myopathy ?
    ### Response:
    Idiopathic inflammatory myopathy is a group of disorders characterized by inflammation of the muscles used for movement (skeletal muscles). Idiopathic inflammatory myopathy usually appears in adults between ages 40 and 60 or in children between ages 5 and 15, though it can occur at any age.
    