Splenomegaly is a condition that occurs when your spleen becomes enlarged. It is also commonly referred to as enlarged spleen or spleen enlargement. The spleen is a part of your lymphatic system. The spleen helps the immune system by storing white blood cells and helping in the creation of antibodies. The spleen is found on the left side of your body, below your rib cage. It is responsible for filtering antibody-coated bacteria, reprocessing old red blood cells, and recycling the iron in the hemoglobin. Your spleen is extremely important in your body’s fight against infection because it is the source of your white blood cells. White blood cells protect your body from bacteria and infections. The spleen is usually about the size of your fist, but when enlarged, it can become much bigger.