The lymphoma cells in WM grow mainly in the bone marrow, where they can crowd out the normal cells that make the different blood cells. This can lead to low levels of red blood cells (called anemia), which can cause people to feel tired and weak. It can also cause low numbers of white blood cells, which makes it hard for the body to fight infection. The amount of platelets in the blood can also get low, leading to increased bleeding and bruising.

Lymphoma cells can also grow in organs like the liver and spleen, causing these organs to swell and leading to abdominal pain. The macroglobulin that is made by the lymphoma cells can cause other problems as well.

Lymphoid tissue and the immune system

Lymphoid tissue contains several types of immune system cells that work together to resist infections. Lymphoid tissue also reacts to transplanted tissues (such as blood transfusions or organ transplants) from other people and is involved in fighting some types of cancer.

Lymphoid tissue is found in lymph nodes, which are pea-sized collections of immune system cells found in the underarm area, in the groin, on the sides of the neck, inside the chest, and inside the abdomen. Lymphoid tissue is found in the bone marrow as well as other organs such as the thymus (found behind the chest bone and in front of the heart), the spleen (on the left side of the abdomen next to the stomach), and the tonsils and adenoids. Lymphoid tissue is also scattered throughout the body within other systems such as the digestive system and respiratory system.

Lymphocytes (lymph cells) are the main cell of lymphoid tissue. There are 2 types of lymphocytes: T cells and B cells. B cells respond to an infection by changing into a different type of cell called a plasma cell. Plasma cells make the antibodies (also called immunoglobins) that help the body attack and kill disease-causing germs such as bacteria. The main job of T cells is to help direct the immune response, but they also can directly kill invading infections.

Cells responsible for Waldenstrom macroglobulinemia

Waldenstrom macroglobulinemia is a cancer of the B cells. The cancer cells in people with Waldenstrom macroglobulinemia are similar to those of 2 other types of cancer: multiple myeloma and non-Hodgkin lymphoma. Multiple myeloma is considered a cancer of plasma cells and non-Hodgkin lymphoma is a cancer of lymphocytes. The cells of WM have features of both plasma cells and lymphocytes and are called lymphoplasmacytoid. These cells produce large amounts of an abnormal type of antibody protein (immunoglobulin M, or IgM) that causes many of the symptoms of Waldenstrom macroglobulinemia, including excessive bleeding, problems with vision, and nervous system problems.