(See also Overview of Bacterial Skin Infections Overview of Bacterial Skin Infections The skin provides a remarkably good barrier against bacterial infections. Although many bacteria come in contact with or reside on the skin, they are normally unable to establish an infection... read more .)
Lymph is a fluid that oozes out of the body's tiniest blood vessels. The fluid goes between cells and brings nourishment and carries away damaged cells, cancer cells, and infectious microorganisms. All lymph passes through lymphatic vessels to strategically placed lymph nodes. Lymph nodes filter damaged cells, cancer cells, and foreign particles out of the lymph fluid. Special white blood cells in lymph nodes engulf and destroy damaged cells, cancer cells, infectious organisms, and foreign particles.
Lymphadenitis almost always results from an infection, which may be caused by bacteria, viruses, protozoa, 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 Infectious Mononucleosis Epstein-Barr virus causes a number of diseases, including infectious mononucleosis. The virus is spread through kissing. Symptoms vary, but the most common are extreme fatigue, fever, sore throat... read more , cytomegalovirus infection Cytomegalovirus (CMV) Infection Cytomegalovirus infection is a common herpesvirus infection with a wide range of symptoms: from no symptoms to fever and fatigue (resembling infectious mononucleosis) to severe symptoms involving... read more , streptococcal infection Streptococcal Infections Streptococcal infections are caused by any one of several species of Streptococcus. These gram-positive, sphere-shaped (coccal) bacteria (see figure How Bacteria Shape Up) cause many disorders... read more , tuberculosis Tuberculosis (TB) Tuberculosis is a chronic contagious infection caused by the airborne bacteria Mycobacterium tuberculosis. It usually affects the lungs. Tuberculosis is spread mainly when people breathe air... read more , or syphilis Syphilis Syphilis is a sexually transmitted disease caused by the bacteria Treponema pallidum. Syphilis can occur in three stages of symptoms, separated by periods of apparent good health. It begins... read more . The infection may affect many lymph nodes or only those in one area of the body.
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 Cellulitis Cellulitis is a spreading bacterial infection of the skin and the tissues immediately beneath the skin. This infection is most often caused by streptococci or staphylococci. Redness, pain, and... read more . People commonly have a fever. Occasionally, pockets of pus (abscesses Skin abscesses Folliculitis and skin abscesses are pus-filled pockets in the skin resulting from bacterial infection. They may be superficial or deep, affecting just hair follicles or deeper structures within... read more ) develop.
Enlarged lymph nodes that do not cause pain, tenderness, or redness may indicate a serious different disorder, such as lymphoma Overview of Lymphoma Lymphomas are cancers of lymphocytes, which reside in the lymphatic system and in blood-forming organs. Lymphomas are cancers of a specific type of white blood cells known as lymphocytes. These... read more , tuberculosis Tuberculosis (TB) Tuberculosis is a chronic contagious infection caused by the airborne bacteria Mycobacterium tuberculosis. It usually affects the lungs. Tuberculosis is spread mainly when people breathe air... read more , or Hodgkin lymphoma Hodgkin Lymphoma Hodgkin lymphoma is a type of lymphoma distinguished by the presence of a particular kind of cancer cell called a Reed-Sternberg cell. The cause is unknown. Lymph nodes enlarge but are usually... read more . Such lymph nodes require a doctor’s attention.
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 depends on the organism causing the infection. For a bacterial infection, an antibiotic is usually given by vein (intravenously) or by mouth. Other drugs are given for a fungal or parasitic infection.
Hot, 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 Skin abscesses Folliculitis and skin abscesses are pus-filled pockets in the skin resulting from bacterial infection. They may be superficial or deep, affecting just hair follicles or deeper structures within... read more must be drained surgically, and people are given intravenous antibiotics. In children, intravenous antibiotics are commonly needed.