Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Multicentric Castleman Disease ?
    ### Response:
    Multicentric Castleman disease (MCD) is a rare condition that affects the lymph nodes and related tissues. It is a form of Castleman disease that is "systemic" and affects multiple sets of lymph nodes and other tissues throughout the body (as opposed to unicentric Castleman disease which has more "localized" effects).
    