Lymph nodes are part of the lymph system. The lymph system helps the body fight infection. It includes the lymph nodes, lymph vessels, and other parts of the body's immune and blood-forming systems, such as the spleen and bone marrow.
The lymph nodes are small, oval-shaped organs in the neck, armpits, groin, and elsewhere throughout the body. Lymph nodes make and store infection-fighting white blood cells called lymphocytes and monocytes. These blood cells are carried in the lymph fluid. The lymph nodes also filter the lymph fluid, keeping bacteria and other organisms out of the bloodstream. The nodes may also trap cancer cells. The lymph vessels link all the nodes in the body and carry the lymph fluid to other parts of the body.
Lymph nodes are also called lymph glands even though they are not really glands.
The nodes get bigger when they fight germs or cancer. For example, they may become enlarged because of:
Often when the lymph nodes are fighting infection, they are also tender if touched. Sometimes the lymph node itself gets infected. Usually it will be tender when this happens, but not always.
Once the lymph nodes become enlarged, they often do not completely go back to their original size. It is not unusual, for example, to feel enlarged lymph nodes in the groin because of a previous injury to the legs, such as a stubbed toe or skinned knee.
The symptoms of enlarged lymph nodes include:
Lymph nodes that are swollen for more than a couple of weeks should be checked by your healthcare provider. Treatment is not always necessary, but when it is, the type of treatment depends on your medical history, physical exam, lab tests, and why the nodes are enlarged.
Call your provider if swollen lymph nodes: