Enlarged Spleen

Alternative Names: Splenomegaly.

Spleen enlargement is an enlargement of the spleen beyond its normal size.  The spleen is located on the left side of the abdomen and weighs around 200g (8oz) in the average healthy adult.  The spleen can be considered a dual-purpose organ: it filters the blood and removes abnormal cells (such as old and defective red blood cells), and it makes disease-fighting components of the immune system (including antibodies and lymphocytes).  Since the spleen is involved in so many bodily functions, it is vulnerable to a wide range of disorders involving the blood or lymph system, and by infection, malignancies, liver disease, or parasites. The body of the spleen appears red and pulpy, surrounded by a tough capsule.  The red pulp consists of blood vessels (splenic sinusoids) interwoven with connective tissue (splenic cords).  The red pulp filters the blood and removes old and defective blood cells.  The white pulp is inside the red pulp, and consists of little lumps of lymphoid tissue.  Antibodies are made inside the white pulp.  Similar to other organs of the lymphatic system, particular immune cells (B-lymphocytes and T-lymphocytes) and blood cells are either made or matured inside the spleen.  Blood enters the spleen via the splenic artery, which subdivides into many tiny branches.  Each branch is encased in a clump of lymphocytes, which means every drop of blood is filtered for foreign particles as it enters the spleen.

Hypersplenism is the name given to the condition where the spleen becomes overactive and destroys more blood cells than it should.  Symptoms depend on which blood component is lacking.  For example, if red blood cells are deficient, anaemia will result (with symptoms including fatigue and pallor).  Most cases of hypersplenism are caused by disorders somewhere else in the body, such as cirrhosis of the liver.

Splenic rupture can be caused by certain disorders such as infectious mononucleosis: the spleen becomes delicate enough to spontaneously rupture.  A sudden blow to the abdomen can split the outer capsule of the spleen and cause bleeding into the abdominal cavity.  There are various degrees of splenic rupture.  When bleeding is life-threatening, surgery to remove the spleen (splenectomy) is needed.

Incidence; Causes and Development

Splenomegaly occurs in about 10% of systemic lupus erythematosus patients.

A variety of disorders can cause the spleen to enlarge, sometimes to 2kg (roughly 4lbs) or more.  Any condition that causes a rapid breakdown of blood cells, such as haemolytic anaemia, can place great strain on the spleen and make it enlarge.  This includes:

• Infections
  
  • Infectious mononucleosis (EBV or CMV), "glandular fever"
  • Other viral infections
  • Parasitic infections
  • Cat scratch disease
  • Bacterial infections
• Liver Diseases
  
  • Cirrhosis (portal vein obstruction, portal hypertension)
  • Sclerosing cholangitis
  • Wilson's disease
  • Biliary atresia
  • Cystic fibrosis
• Hemolytic anemias
  
  • Thalassemia
  • Hemoglobinopathies
  • Hemolytic anemia due to G6PD deficiency
  • Idiopathic autoimmune hemolytic anemia
  • Immune hemolytic anemia
• Cancers
  
  • Leukemia
  • Lymphoma
  • Hodgkin's disease
• Other causes
  
  • Sarcoidosis
  • Sickle cell splenic crisis
  • Banti's syndrome
  • Felty syndrome

Signs and Symptoms

Although often there are no symptoms, there may be pain in the left upper section of the abdomen.  If this pain is present, especially if it is severe or gets worse when taking a deep breath, then medical attention should be sought immediately.  An enlarged spleen may also cause a premature feeling of fullness at meals.

Diagnosis and Tests

Depending on the condition under investigation, disorders of the spleen can be diagnosed using a number of tests, including:

• Physical examination.  A physician will tap along the left-upper quadrant of the abdomen and feel in that same area, especially just under the rib cage.
• Blood tests such as a CBC
• Ultrasound
• Abdominal film or CT scan
• Bone marrow biopsy
• Other tests to check for underlying disorders.

The physician will also ask a series of questions to determine if there are symptoms either from the enlarged spleen or the underlying cause of the large spleen.

Treatment and Prevention

Appropriate limitation of activity, including avoiding contact sports, will help prevent trauma that might cause the spleen to rupture.

Prognosis; Complications

Care will be required for the specific condition causing the splenomegaly.

Rupture of the enlarged spleen is particularly possible in infectious mononucleosis and several other causes of splenomegaly.