What causes an enlarged spleen?
The spleen will enlarge when it performs more of its duties to filter blood or to manufacture blood cells. Therefore, any disease or condition that damages red blood cells, and requires them to be filtered and removed from the blood stream, will cause the spleen to become larger.
Conditions such as hemolytic anemia, where red blood cells are damaged and broken down (hemolyzed) can cause the spleen to enlarge. Misshapen red blood cells, like those found in sickle cell disease, thalassemia, and spherocytosis, may be damaged when they try to squeeze through small capillary blood vessels. These damaged red blood cells need to be culled from the bloodstream and are filtered out by the spleen.
Decreased blood flow
The spleen will enlarge if there is a decrease in blood flow through the splenic vein. This may cause spleen congestion and enlargement. This situation may be associated with liver disease and portal hypertension. Damage to liver cells makes it difficult for blood to flow normally, and as blood backs up in the portal vein system, it may affect pressure in the splenic vein. The decreased ability of blood to drain from the spleen causes it to become congested and grow larger. People with congestive heart failure may have an enlarged liver and spleen because of poor blood flow to and from the heart.
Leukemia and lymphoma may be associated with abnormal white cells that can invade the spleen and increase its size.
Other cancers can spread or metastasize to the spleen and cause it to enlarge.
Certain metabolic diseases may cause the spleen to enlarge, including Hurler Syndrome, Gaucher disease and Niemann-Pick Disease.
In sarcoidosis and amyloidosis the spleen can be involved and become enlarged with the abnormal protein deposits.
Some infections may cause splenomegaly including:
Trauma, for example, from a car accident, can damage the spleen.