The spleen sits directly above the stomach and under the ribs on the left side. It is approximately the size of a fist and is part of the lymphatic system, according to Medline Plus. The lymphatic system fights infection and keeps body fluids in balance. The spleen consists of white blood cells used to fight germs, regulate blood supply and destroy old and damaged cells. Medical conditions, injuries or blood disorders can cause tenderness and pain in the spleen.
Sickle Cell Disease
Sickle-cell disease can cause an enlarged and tender spleen when blood cells pool within the spleen. Sickle-cell disease, an inherited blood disorder, consists of abnormal hemoglobin, proteins in red blood cells responsible for carrying oxygen through the body, according to the Children Hospital Boston. A person with sickle-cell disease has his red blood cells change from round and soft to rigid and "sickle" shaped. The abnormally shaped blood cells clump together blocking blood flow to small blood vessels. Sickle-cell disease can cause a tender spleen as a result of splenic sequestration, a condition in which red blood cells get trapped within the spleen, preventing blood from circulating to the heart and brain. Trapped red blood cells can cause a tender spleen as it enlarges and bulges into the upper left part of the abdomen.
An injured or ruptured spleen can be especially painful and tender, according to The Merck Manuals Online Medical Library. A severe blow to the stomach can damage the spleen, tearing its covering and destroying the tissue inside. Tears to the spleen can range from small ones that stop bleeding suddenly to very large ones that cause severe bleeding or hemorrhaging. In some severe cases, blood or a hematoma forms deep within the spleen causing severe pain and tenderness.
A tender spleen may be caused by a blood disorder called polycythemia vera. Polycythemia vera occurs when bone marrow cells rapidly increase causing an enlarged and tender spleen, according to the MayoClinic.com. This disorder is typically triggered by changes in the DNA of a single bone marrow cell. Polycythemia vera slows blood flow and causes blood to thicken increasing the risk of developing blood clots. People with polycythemia vera report a feeling of fullness or bloating in their left upper abdomen due to an enlarged spleen. It usually occurs in patients over 50 years of age but can occur earlier or later, according to the Arizona Telemedicine Program.