Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) familial cylindromatosis ?
    ### Response:
    Familial cylindromatosis is a condition involving multiple skin tumors that develop from structures associated with the skin (skin appendages), such as hair follicles and sweat glands. People with familial cylindromatosis typically develop large numbers of tumors called cylindromas.
    