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• Many disorders, including infections, anemias, and cancers, can cause an enlarged spleen.
• Symptoms are usually not very specific but can include fullness or pain in the upper left abdomen or back.
• Usually doctors can feel an enlarged spleen, but x-rays and other imaging tests may be used to determine how large the spleen is.
• Treating the disorder that is causing the spleen to enlarge usually takes care of the problem, but sometimes the spleen must be removed.

An enlarged spleen (splenomegaly) is not a disease in itself but the result of an underlying disorder. Many disorders can make the spleen enlarge. To pinpoint the cause, doctors must consider disorders ranging from chronic infections to blood cancers.

When the spleen enlarges, it traps and stores an excessive number of blood cells and platelets (hypersplenism), thereby reducing the number of blood cells and platelets in the bloodstream. This process creates a vicious circle: the more cells and platelets the spleen traps, the larger it grows; the larger it grows, the more cells and platelets it traps. Eventually, the greatly enlarged spleen also traps normal red blood cells, destroying them along with the abnormal ones. In addition, excessive numbers of blood cells and platelets can clog the spleen, interfering with its functioning.

Did You Know... An enlarged spleen is not a disease itself but a result of an underlying disorder.

An enlarged spleen may outgrow its own blood supply. When parts of the spleen do not get enough blood, they may become damaged, causing them to bleed or die.

Causes of an Enlarged Spleen Infections Brucellosis Hepatitis Infectious mononucleosis Kala-azar Malaria Psittacosis Subacute bacterial endocarditis Syphilis Tuberculosis Anemias Hereditary elliptocytosis Hereditary spherocytosis Sickle cell disease (mainly in children) Thalassemia Blood cancers and myeloproliferative disorders Hodgkin lymphoma and other lymphomas Leukemia Myelofibrosis Polycythemia vera Storage diseases Gaucher's disease Hand-Schüller-Christian disease Letterer-Siwe disease Niemann-Pick disease Wolman's disease Other causes Amyloidosis Blood clot in a vein from the spleen or to the liver Cirrhosis Cysts in the spleen External pressure on veins from the spleen or to the liver Felty's syndrome Sarcoidosis Systemic lupus erythematosus (lupus)

Symptoms

An enlarged spleen does not cause many symptoms, and the symptoms that it does cause may be mistaken for many other medical conditions. Because the enlarged spleen lies next to the stomach and sometimes presses against it, people may feel full after eating a small snack or even without eating. People may also have abdominal or back pain in the area of the spleen. The pain may spread to the left shoulder, especially if parts of the spleen do not get enough blood and start to die.

When the spleen removes too many blood cells and platelets from the bloodstream, a variety of problems may develop. These problems include anemia as a result of too few red blood cells, frequent infections as a result of too few white blood cells, and the tendency to bleed as a result of too few platelets.

Diagnosis

Doctors may suspect that the spleen is enlarged when people complain of fullness or pain in the upper left portion of the abdomen or back. Usually, doctors can feel an enlarged spleen during a physical examination. An x-ray of the abdomen may also show that the spleen is enlarged. In some cases, ultrasonography or computed tomography (CT) is needed to determine how large the spleen is and whether it is pressing on other organs. Magnetic resonance imaging (MRI) provides similar information and also traces blood flow through the spleen. Other specialized scanning devices use mildly radioactive particles to assess the spleen's size and function and to determine whether it is accumulating or destroying large numbers of blood cells.

Blood tests show decreased numbers of red blood cells, white blood cells, and platelets. When blood cells are examined under a microscope, their shape and size may provide clues to the cause of the spleen enlargement. An examination of bone marrow (see Symptoms and Diagnosis of Blood Disorders: Bone Marrow Examination) may show cancer of the blood cells (such as leukemia or lymphoma) or an accumulation of unwanted substances (such as occurs in storage diseases). Blood protein measurement can determine whether other conditions are present that can cause the spleen to enlarge, such as amyloidosis, sarcoidosis, malaria, kala-azar, brucellosis, and tuberculosis. Liver function tests help determine whether the liver is also diseased.

Doctors cannot easily remove a sample of the spleen for examination because inserting a needle or cutting spleen tissue may cause uncontrollable bleeding. If an enlarged spleen is removed during surgery to diagnose or treat certain diseases, the spleen is sent to a laboratory, where the cause of enlargement can usually be determined.

Treatment

When possible, doctors treat the underlying disorder that caused the enlarged spleen. Surgical removal of the spleen (splenectomy) may be necessary but can cause problems, including an increased susceptibility to infections. However, the risks are worth taking in certain critical situations:

• When the spleen destroys red blood cells so rapidly that severe anemia develops
• When the spleen so depletes stores of white blood cells that infection is likely
• When the spleen so depletes stores of platelets that bleeding is likely
• When the spleen is so large that it causes pain or puts pressure on other organs
• When the spleen is so large that parts of it bleed or die

As an alternative to surgery, radiation therapy can sometimes be used to shrink the spleen.

Last full review/revision June 2008 by Harry S. Jacob, MD