Spleen in Waldenstrom's disease. Gross specimen of a spleen from a patient with Waldenstrom's disease, or macroglobulinaemia. This is a cancer of lymphatic tissue that causes the proliferation of plasma cells, which produce the antibody IgM (an immunoglobulin). The overabundance of plasma cells causes raised levels of IgM, which thickens the blood. The thickening leads to fatigue, weight loss, dizziness and a lack of coordination. In severe cases, heart failure may result. The spleen and lymph nodes may also swell. Treatment is by plasmapheresis, the separation of the blood to remove excess IgM. Chemotherapy is also used to treat the cancer.