The lymphatic system is a complex network of thin vessels, valves, ducts, nodes, and organs. It helps to protect and maintain the fluid environment of the body by producing, filtering, and conveying lymph and by producing various blood cells. Lymph nodes play an important part in the body's defense against infection. The most common cause of swollen lymph nodes is infection, which might occur even if the infection is trivial or not. Afferent lymph vessels bring unfiltered fluids into the lymph node to be filtered while efferent vessels carry clean fluids away from the lymph node and to the cardiovascular system where it helps form the plasma in the blood. Overall, lymph nodes work like a biological filtering system. When the body is invaded by foreign organisms, the painful swelling sometimes felt in the neck, armpits, groin, or tonsils comes from the microorganisms being trapped inside collections of lymph cells or nodes. Eventually, these organisms are destroyed and eliminated by cells that line the walls of the lymph nodes and the swelling and pain subside.
What are lymph nodes? Lymph nodes are small, bean-shaped glands throughout the body. They are part of the lymph system, which carries fluid (lymph fluid), nutrients, and waste material between the body tissues and the bloodstream.
The lymph system is an important part of the immune system, the body's defense system against disease. The lymph nodes filter lymph fluid as it flows through them, trapping bacteria, viruses, and other foreign substances, which are then destroyed by special white blood cells called lymphocytes. Lymph nodes may be found singly or in groups. And they may be as small as the head of a pin or as large as an olive. Groups of lymph nodes can be felt in the neck, groin, and underarms. Lymph nodes generally are not tender or painful. Most lymph nodes in the body cannot be felt.
What causes swollen lymph nodes? Lymph nodes often swell in one location when a problem such as an injury, infection, or tumor develops in or near the lymph node. Which lymph nodes are swollen can help identify the problem. The glands on either side of the neck, under the jaw, or behind the ears commonly swell when you have a cold or sore throat. Glands can also swell following an injury, such as a cut or bite, near the gland or when a tumor or infection occurs in the mouth, head, or neck. Glands in the armpit (axillary lymph nodes) may swell from an injury or infection to the arm or hand. A rare cause of axillary swelling may be breast cancer or lymphoma. The lymph nodes in the groin (femoral or inguinal lymph nodes) may swell from an injury or infection in the foot, leg, groin, or genitals. In rare cases, testicular cancer, lymphoma, or melanoma may cause a lump in this area. Glands above the collarbone (supraclavicular lymph nodes) may swell from an infection or tumor in the areas of the lungs, breasts, neck, or abdomen. Common sites for swollen lymph nodes camera.gif include the neck, groin, and underarms.
What does it mean when lymph nodes swell in two or more areas of the body? When lymph nodes swell in two or more areas of the body, it is called generalized lymphadenopathy. This may be caused by: A viral illness, such as measles, rubella, chickenpox (varicella), or mumps. Mononucleosis (Epstein-Barr virus), which results in fever, sore throat, and fatigue, or cytomegalovirus (CMV), a viral infection that causes symptoms similar to those of mononucleosis. A bacterial illness, such as strep throat (caused by the streptococcus bacterium) or Lyme disease (a bacterial infection spread by certain types of ticks). Side effects of phenytoin (Dilantin), a medicine used to prevent seizures. Side effects of measles-mumps-rubella (MMR) vaccination. Cancer, such as leukemia, Hodgkin's disease, and non-Hodgkin's lymphoma. Acquired immunodeficiency syndrome (AIDS), which develops after a person contracts HIV (human immunodeficiency virus). This virus attacks the immune system, making it difficult for the body to fight off infection and some disease. Syphilis, a sexually transmitted infection.
How are swollen lymph nodes treated? Treatment for swollen glands focuses on treating the cause. For example, a bacterial infection may be treated with antibiotics, while a viral infection often goes away on its own. If cancer is suspected, a biopsy may be done to confirm the diagnosis. Any swollen lymph nodes that don't go away or return to normal size within about a month should be checked by your doctor. How long will lymph nodes remain swollen? Lymph nodes may remain swollen or firm long after an initial infection is gone. This is especially true in children, whose glands may decrease in size while remaining firm and visible for many weeks.
Once a bacterial infection is detected, it is only a matter of hours before the lymph nodes begin to swell with T cells, the main soldiers of the immune system.