Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) giant congenital melanocytic nevus ?
    ### Response:
    Giant congenital melanocytic nevus is a skin condition characterized by an abnormally dark, noncancerous skin patch (nevus) that is composed of pigment-producing cells called melanocytes. It is present from birth (congenital) or is noticeable soon after birth.
    