Lymphadenitis is infection of one or more lymph nodes, which usually become swollen and tender.
(See also Overview of Bacterial Skin Infections.)
Lymph is a fluid that oozes out of the body's tiniest blood vessels and is part of the body’s immune system. The fluid goes between cells and brings nourishment and carries away substances such as damaged cells, cancer cells, and infectious microorganisms. All lymph passes through lymphatic vessels to strategically placed lymph nodes. Lymph nodes and specialized white blood cells in lymph nodes work to remove these substances and foreign particles from the body. (See figure Lymphatic System: Helping Defend Against Infection.)
Lymphadenitis almost always results from an infection, which may be caused by bacteria, viruses, parasites, or fungi. Typically, the infection spreads to a lymph node from a skin, ear, nose, or eye infection or from such infections as infectious mononucleosis, cytomegalovirus infection, streptococcal infection, tuberculosis, or syphilis. The infection may affect many lymph nodes or only those in one area of the body.
Symptoms of Lymphadenitis
Infected lymph nodes enlarge and are usually tender and painful. Sometimes, the skin over the infected nodes is inflamed, looks red, and feels warm. Some people may have cellulitis. People commonly have a fever. Occasionally, pockets of pus (abscesses) develop.
Enlarged lymph nodes that do not cause pain, tenderness, or redness may indicate a serious, different disorder, such as lymphoma. Such lymph nodes require a doctor’s attention.
Diagnosis of Lymphadenitis
A doctor's evaluation
Sometimes aspiration and culture or a tissue biopsy
Usually, lymphadenitis can be diagnosed based on the symptoms, and its cause is an obvious nearby infection.
When the cause cannot be identified easily, a doctor inserts a needle into a lymph node and withdraws (aspirates) fluid. The fluid sample is then sent to a laboratory for culture (the sample is placed in a culture medium that allows microorganisms to grow). The culture can identify the organism causing the infection. Alternatively, the doctor can do a biopsy (removal and examination of a piece of the lymph node under a microscope).
Treatment of Lymphadenitis
Antibiotics
Treatment of lymphadenitis depends on the organism causing the infection. For a bacterial infection, an antibiotic is usually given by vein (intravenously) or by mouth. Other medications are given for a fungal or parasitic infection.
Warm, wet compresses may help relieve the pain in inflamed lymph nodes. Usually, once the infection has been treated, the lymph nodes slowly shrink, and the pain subsides. Sometimes the enlarged nodes remain firm but no longer feel tender.
Abscesses must be drained surgically, and people are given intravenous antibiotics. In children, intravenous antibiotics are commonly needed.
