Lymphadenitis

Lymphadenitis is inflammation of one or more lymph nodes, which usually become swollen and tender. Lymphadenitis is almost always caused by an infection, which may be due to bacteria, viruses, protozoa, rickettsiae, 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 and Diagnosis
Infected lymph nodes enlarge and are usually tender and painful. Sometimes, the skin over the infected nodes looks red and feels warm. Occasionally, pockets of pus (abscesses) develop. Enlarged lymph nodes that do not produce pain, tenderness, or redness may indicate a serious disorder, such as lymphoma, tuberculosis, or Hodgkin's disease. Such lymph nodes require a
doctor's attention.
Usually, lymphadenitis can be diagnosed on the basis of symptoms, and its cause is an obvious nearby infection. When the cause cannot be identified easily, a biopsy (removal and examination of a tissue sample under a microscope) and culture may be needed to confirm the diagnosis and to identify the organism causing the infection.

Treatment and Prognosis
Treatment depends on the organism causing the infection. For a bacterial infection, an antibiotic is usually given intravenously or orally. Warm 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.
(Merck)