The spleen sits under your rib cage in the upper left part of abdomen toward the back. It is an organ that is part of the lymph system and works as a drainage network that defends our body against infection. A spleen is normally about the size of a fist. But diseases can cause it to swell and become many times its normal size. Because the spleen is involved in many functions, many conditions may affect it. An enlarged spleen is not always a sign of a problem. When a spleen becomes enlarged, though, it often means it has been doing its job but has become overactive.
An enlarged spleen can be caused by infections, cirrhosis and other liver diseases, blood diseases characterized by abnormal blood cells, problems with the lymph system, or other conditions.
Pain or fullness in the left upper abdomen that may spread to the left shoulder
Feeling full without eating or after eating only a small amount