Lymphatic System

Although lymph nodes commonly enlarge to fight infection, an overwhelming infection can leave a lymph node and travel through the lymphatic system to other nodes and even to other body tissues. Cancer can spread very easily through the lymph system, but different cancers vary in how soon they attack the nodes. Lymphedema, fluid accumulation, can occur when the movement of fluid in a lymphatic region is blocked. Although lymphedema is rare, limbs are the most commonly affected areas.

The unregulated growth of cells and tissues of the lymphatic system can lead to lymphoma, or lymph cancer. Lymphomas are classified into two types, Hodgkin's or non-Hodgkin's, both of which can be malignant. Hodgkin's disease is marked by enlargement of lymph nodes, usually those in the neck. Symptoms of Hodgkin's include chronic fatigue, depressed immune function, weight loss, night sweats, and pain after drinking alcohol. Hodgkin's is diagnosed by lymph node biopsy, with identification confirmed by the presence of Reed-Sternberg cells, large multinucleated cells. Hodgkin's is further categorized as lymphocyte predominant, nodular sclerosis, mixed cellularity, or lymphocyte-depleted on the basis of the cell populations present in the biopsy sample. Hodgkin's can be successfully treated and cured with radiation or chemotherapy if it is caught in its early stages. Although the cause of Hodgkin's is unknown, males, Caucasians, people of higher socioeconomic status, the well-educated, and people with certain blood types are more prone to develop it. Hodgkin's most often affects people in their 20s or 70s for unknown reasons. People who work with certain chemicals, such as benzene and rubber products, also seem to be more prone to develop the disease.

Non-Hodgkin's lymphoma is also diagnosed through lymph tissue biopsy. Several lymphomas have been identified, but have little in common. Burkitt's lymphoma, prevalent among Central African children, is characterized by enlargement of the lymph nodes under the jaw. In contrast with most lymphomas whose causes are unclear, Burkitt's lymphoma has been linked to infection with the Epstein-Barr virus. Mycosis fungoides is a rare T cell lymphoma that affects the skin.

Non-Hodgkin's lymphomas are further classified as lymphocytic or histiocytic. Lymphocytic lymphomas may be poorly differentiated (according to the extent to which they have evolved from the pluri potential stem cell); they may also be nodular (concentrated) or diffuse.

Symptoms for most lymphomas are similar. Many patients experience enlargement of the liver and spleen as well as the lymph nodes. Some patients have bloody stools or vomit blood. Tiredness, itching, weight loss, fever, and general immunosuppression may also be present. The symptoms may abate and intensify over several months before a diagnosis is made. Sometimes, a bone marrow biopsy is also performed. Treatment includes radiation or chemotherapy with effectiveness varying according to severity of the lymphoma at the time of diagnosis. Bone marrow transplants have been effective against some advanced-stage lymphomas. The "cure" rate for non-Hodgkin's lymphomas is generally poorer than for Hodgkin's lymphomas.