Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Waldenstrm macroglobulinemia ?
    ### Response:
    Waldenstrm macroglobulinemia is a rare blood cell cancer characterized by an excess of abnormal white blood cells called lymphoplasmacytic cells in the bone marrow. This condition is classified as a lymphoplasmacytic lymphoma. The abnormal cells have characteristics of both white blood cells (lymphocytes) called B cells and of more mature cells derived from B cells known as plasma cells.
    