Lymph nodes are tiny, bean shaped organs that filter lymph fluid. They are located throughout the body, but particular collections are found just under the skin in the neck, under the arms, and in the groin area. Lymph nodes are part of the lymphatic system (see Biology of the Immune System: Lymphatic System: Helping Defend Against Infection), which is one of the body's defense mechanisms against the spread of infection and cancer.
Lymph is clear fluid that is made up of water, white blood cells, proteins, and fats that have filtered out of blood vessels into the spaces between cells. Some of the fluid is reabsorbed by the blood vessels but the rest enters the lymphatic vessels. Lymph then passes through the lymph nodes, which are specific collection points where damaged cells, infectious organisms, and cancer cells are filtered from the fluid and destroyed. If many infectious organisms or cancer cells are present, the lymph nodes swell. Sometimes, organisms cause infection within a lymph node.
A few small nodes often can be felt in healthy people. Lymph nodes that are larger and easily felt may be a sign of a disorder. Some people use the term "swollen glands" to refer to swollen lymph nodes, especially when the nodes in the neck are swollen. However, lymph nodes are not glands. Doctors use the term lymphadenopathy to refer to swollen lymph nodes.
Lymph nodes in only one body area may be swollen, or nodes in two or more body areas can be swollen. When swollen lymph nodes are painful or have signs of inflammation (for example, redness or tenderness), the condition is termed lymphadenitis. Other symptoms, such as sore throat, runny nose, or fever, may be present, depending on the cause. Sometimes swollen lymph nodes are discovered when the person is being examined because of another symptom.
Because lymph nodes participate in the body's immune response, a large number of infections, inflammatory disorders, and cancers are potential causes. Only the more common causes are discussed here.
The most common causes are
Sometimes doctors cannot determine the cause of the swelling, but swelling goes away on its own without causing the person any harm.
The most dangerous causes are cancer, human immunodeficiency virus (HIV) infection, and tuberculosis. However, probably less than 1% of people with swollen lymph nodes have cancer.
Not every person with swollen lymph nodes requires immediate evaluation by a doctor. The following information can help people decide when a doctor's evaluation is needed and help them know what to expect during the evaluation.
In people with swollen lymph nodes, certain symptoms and characteristics are cause for concern. They include
When to see a doctor:
If a lymph node is very painful or draining pus or other material, people should see a doctor right away. Other people should call their doctor. The doctor will decide how quickly they need to be seen based on the presence of warning signs and other symptoms. For people who have no warning signs and otherwise feel well, a delay of a week or so is not harmful.
What the doctor does:
The doctor first asks questions about the person's symptoms and medical history. Doctors then do a physical examination. What they find during the history and physical examination often suggests a cause of the swollen lymph nodes and the tests that may need to be done (see Lymphatic Disorders: Some Causes and Features of Swollen Lymph Nodes).
Doctors then do a physical examination. Doctors check for fever and examine areas where lymph nodes are found. Doctors check the person for any signs of infection or lumps elsewhere in the body. People who have swollen lymph nodes throughout the body usually have a disorder that affects the entire body. However, people who have swollen lymph nodes in only one area may have a disorder that affects only that area (for example, an infection) or more widespread disease.
Sometimes the history and physical examination suggest the cause, as for example when the person has an upper respiratory infection or a dental infection (see Lymphatic Disorders: Some Causes and Features of Swollen Lymph Nodes). In other cases, findings do not point to a single cause. People with warning signs are more likely to have a serious disorder, but people with lymph node swelling and no other symptoms may also have a serious disorder.
Nodes that are hard, very enlarged, and do not move when pushed may indicate cancer. Tenderness, redness, and warmth in a single enlarged lymph node may indicate an infection of the node.
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If doctors suspect a specific disorder (for example, mononucleosis in a young person with fever, sore throat and an enlarged spleen), initial testing is directed at that condition (see Lymphatic Disorders: Some Causes and Features of Swollen Lymph Nodes).
If history and physical examination do not show a likely cause, further testing depends on the nodes involved and the other findings present.
People with warning signs and those with widespread lymph node swelling should have a complete blood count and chest x-ray. Doctors may also test for tuberculosis, HIV infection, and mononucleosis. Sometimes blood tests are needed to detect toxoplasmosis and syphilis. In people with joint pain or stiffness or a rash, blood tests are done for systemic lupus erythematosus (lupus).
If doctors suspect cancer or lymphoma, the person has a lymph node biopsy. Biopsy may also be needed when widespread lymph node swelling does not resolve within three to four weeks.
Primary treatment is directed at the cause. Swollen lymph nodes are not treated.
Last full review/revision August 2012 by James D. Douketis, MD