Scattered throughout the bodies are the lymph nodes, fortresses of the body that guard against pathogens or foreign substances that manage to find their way into the body tissue. Within each of these lymph nodes are thousands of lymphocytes, white blood cells which play a variety of functions from destroying tumorous body cells and cells infected with viruses to producing antibodiesin response to antigens. Lymphadenopathy, a condition where the lymph nodes become inflamed, is usually a sign that the lymph node is fighting an infection. However, in a few cases, the inflammation of the lymphic nodes can sometimes be a sign of a more serious condition, such as cancer or a serious infection that could lead to life threatening complications, and thus should never be ignored. Below are some of the most common causes of lymphadenopathy:
Viral or bacterial infections
Viral and bacterial infections are one of the most common causes of lymphadenopathy, especially in young children. Two common viruses that result in lymphadenopathy are Epstein–Barr virus and Cytomegalovirus. Both of these viruses are herpesvirus, a family of double strained DNA viruses.
Everyone is usually infected by the Epstein–Barr virus at least once in their lifetime; however, since the symptoms of the virus are very much like that of a cold or flu, few people ever realize that they are infected. The virus remains in the body as a dominant infection and can be transmitted through saliva and mucus. In adolescence and young adults, it can lead to infectious mononucleosis, a condition characterized by several symptoms including loss of appetite, nausea, headaches and lymptadenopathy. Although the signs of infection usually subside in less than 4 months, in rare cases it can lead to serious complications, including hepatitis and inflammation of the tissues of the brain and heart. Ithas even been linked to some forms of cancer, including nasopharyngeal carcinoma and Burkitt's lymphoma. While antibodies are usually ineffective against an EBV infection, they are often used against bacterial complications of EBV infection such as bacterial tonsillitis, an infection of the tonsil of the back of the throat.
Like EBV infections, Cytomegalovirus is a common viral infection that is often ignored because it usually does not produce any serious symptoms. However, in some cases, especially those where the immune system is weakened, it can lead to symptoms similar to that of mononucleus. The infection usually clears up by itself in a few months at most. The complications of Cytomegalovirus are very rare and include pneumonia and nervous system disorders.
In patients that own or work around cats, a common cause of lymptadenopathy is an infection by the bacteria bartonella. This bacteria can be transmitted from scratches and bites inflicted by cats. The infection is known as cat scratch disease, which can result in fatigue, fevers and headaches, as well as the swelling of the lymph nodes. The infection is usually not serious, and can be treated with antibiotics such as azithromycin.
Several autoimmune diseases are known to cause lymphadenopathy, including rheumatoid arthritis and one form of lupus, systemic lupus erythematosus. In rheumatoid arthritis, lymphocytes attack the tissue near the joints, leading to inflammation which causes the joints to become progressively more crippled. This can result in a deliberating pain and loss of mobility as the condition progresses. The swelling of the lymphic nodes is believed not only to be due to the inflammation of the joint tissue, but also due to abnormalities in the immune system itself.
Systemic lupus erythematosus is a condition where various organs are targeted by the body’s immune system, resulting in their inflammation. Early symptoms include fatigue and loss of appetite, and a butterfly rash on the face. Inflammation of the lungs can lead to pleura, and inflammation of the kidneys can lead to high blood pressure and possibly kidney failure. As this autoimmune disease is caused by a genetic abnormality that affects the body’s ability to differentiate its own cells from foreign substances, it cannot be treated. However, in mild cases, anti-inflammation drugs may reduce, if not eliminate, most of the symptoms.
Many forms of cancer result in lymphadenopathy. Lymphoma, a cancer of the lymph nodes, results in the swelling of the nodes from the uncontrolled division of the lymphocyte white blood cells. There are two types of lymphoma: Hodgkin's lymphoma and Non-Hodgkin’s lymphoma. Both forms of lymphoma can be treated by radiation therapy, and the survival rates for both forms of lymphoma are relatively high, with a 5 year survival rate of 90% for Hodgkin’s lymphoma and a 5 year survival rate of around 69% for Non-Hodgkin’s lymphoma. The swelling of the lymph nodes from other forms of cancer can be attributed to the role of lymphocytes in destroying cancer cells.
In many cases of HIV, lymphadenopathy is the only sign of the HIV infection. The HIV virus affects the lymph nodes by destroying the T cells that it produces. In addition to directly damaging the lymph nodes, HIV can weaken the body’s immune system, making relatively minor infections more serious, resulting in prolonged swelling of the lymph nodes.