From MedlinePlus GeneticsWaldenström macroglobulinemia is a rare blood cell cancer characterized by an excess of abnormal white blood cells in the bone marrow. These abnormal cells have characteristics of both white blood cells (lymphocytes) called B cells and more mature cells derived from B cells known as plasma cells. These abnormal cells with both lymphocyte and plasma characteristics are known as lymphoplasmacytic cells. Due to these cells, Waldenström macroglobulinemia is classified as a lymphoplasmacytic lymphoma. In Waldenström macroglobulinemia, these abnormal cells produce excess amounts of IgM, the largest of a type of protein known as an immunoglobulin; the overproduction of this large protein contributes to the condition's name (macroglobulinemia).
Waldenström macroglobulinemia usually begins in a person's sixties and is a slow-growing (indolent) cancer. Some affected individuals have elevated levels of IgM and lymphoplasmacytic cells but no symptoms of the condition; in these cases, the disease is usually found incidentally by a blood test taken for another reason. These individuals are diagnosed with smoldering (or asymptomatic) Waldenström macroglobulinemia. It can be many years before a person with the condition develops noticable signs and symptoms.
The most common signs and symptoms to first appear in people with Waldenström macroglobulinemia are weakness and extreme tiredness (fatigue) caused by a shortage of red blood cells (anemia). Affected individuals can also experience general symptoms such as fever, night sweats, and weight loss. Some people with Waldenström macroglobulinemia develop a loss of sensation and weakness in the limbs (peripheral neuropathy). Doctors are unsure why this feature occurs, although they speculate that the IgM protein attaches to the protective covering of nerve cells (myelin) and breaks it down. The damaged nerves cannot carry signals normally, leading to neuropathy.
Other features of Waldenström macroglobulinemia are due to the accumulation of lymphoplasmacytic cells in different tissues. For example, accumulation of these cells can lead to an enlarged liver (hepatomegaly), spleen (splenomegaly), or lymph nodes (lymphadenopathy). In the bone marrow, the lymphoplasmacytic cells interfere with normal blood cell development, causing a shortage of healthy blood cells (pancytopenia).
Several other signs and symptoms of Waldenström macroglobulinemia are related to the excess amounts of IgM. Increased IgM can thicken blood and impair circulation, causing a condition known as hyperviscosity syndrome. Features related to hyperviscosity syndrome include bleeding in the nose or mouth, blurring or loss of vision, headache, dizziness, and confusion. In some affected individuals, IgM and other immunoglobulins react to cold temperatures to form gel-like clumps that block blood flow in areas exposed to the cold, such as the hands and feet. These clumped proteins are referred to as cryoglobulins, and their clumping causes a condition known as cryoglobulinemia. Cryoglobulinemia can lead to pain in the hands and feet or episodes of Raynaud phenomenon, in which the fingers and toes turn white or blue in response to cold temperatures. The IgM protein, along with another protein called amyloid, can build up in organs and interfere with their normal function. This buildup causes a condition called amyloidosis. Organs that are typically affected by amyloidosis include the heart, kidneys, liver or spleen. Affected individuals can experience weakness, fatigue, shortness of breath, irregular heartbeat, or joint pain.
https://medlineplus.gov/genetics/condition/waldenstrom-macroglobulinemia