Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Dermatofibrosarcoma protuberans ?
    ### Response:
    Dermatofibrosarcoma protuberans is an uncommon cancer in which tumors arise in the deeper layers of skin. The tumor usually starts as a small, firm patch of skin; it may be purplish, reddish, or flesh-colored. It is commonly found on the torso, usually in the shoulder and chest area.
    