Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Paget disease of bone ?
    ### Response:
    Paget disease of bone is a disorder that involves abnormal bone destruction and regrowth, which results in deformity. This condition can affect any of the bones in the body; but most people have it in their spine, pelvis, skull, or leg bones. The disease may affect only one bone or several bones; but it does not affect the entire skeleton.
    