Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) white sponge nevus ?
    ### Response:
    White sponge nevus is a condition characterized by the formation of white patches of tissue called nevi (singular: nevus) that appear as thickened, velvety, sponge-like tissue. The nevi are most commonly found on the moist lining of the mouth (oral mucosa), especially on the inside of the cheeks (buccal mucosa).
    