Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Acanthoma ?
    ### Response:
    An acanthoma is a small, reddish bump that usually develops on the skin of an older adult.  There are several types of acanthoma, including "acantholytic", "epidermolytic", "clear cell", and "melanoacanthoma".  Though most individuals have only one acanthoma, there have been rare reports of individuals who have developed many.
    