Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Palmoplantar keratoderma ?
    ### Response:
    Palmoplantar keratoderma (PPK) is a group of conditions characterized by thickening of the palms and soles of the feet. PPK can also be an associated feature of different syndromes. In rare forms of palmoplantar keratoderma, other organs in the body may be affected in addition to the skin.
    