Purpose of the Lymphatic System
The lymphatic system is a part of our circulatory system, which also includes veins and arteries. The purpose of the lymphatic system is to:
- Produce disease-fighting cells (lymphocytes) for the immune system which help fight bacteria and viruses
- Collect fluids from our tissue and return those fluids to our bloodstream
- Remove excess protein and bacteria from the body.
The lymphatic system consists of lymph vessels, nodes and Lymph tissue.
Vessels are the channels of the lymphatic system. They contain colorless fluid called lymph. Lymph composition may vary considerably in different parts of the body. It may be composed of any of the following: water, large protein molecules, foreign bodies, white blood cells, waste products from cellular metabolism, lymphocytes, large fat molecules, bacterias, viruses, and cancer cells. The lymph fluid flows through the vessels and gradually enters the bloodstream.
Nodes are the stations of the lymph system. All lymph fluid passes through nodes where the fluid is purified of waste matter and bacteria, and viruses are made harmless. After the nodes purify the fluid, it travels through ducts and is eventually drained back into the venous system. It then travels through the heart and lungs to be used again by our tissues. Lymph nodes are located in many areas of our body.
Lymph tissue is where lymph is formed. Lymph tissue is found throughout the body including tonsils, spleen, intestinal wall and bone marrow.
What is Lymphedema?
Lymphedema is a condition that afflicts an estimated two million people in the United States. It is a chronic, persistent condition characterized by an accumulation of protein-enriched fluid found in the tissue spaces of the body. It is caused by a disruption in the lymphatic system that results in obstructed lymphatic flow. This leads to swelling--most often in the arms and legs, but it can occur in other areas of the body as well. Left untreated, the condition usually deteriorates over time, resulting in reduced skin integrity, fibrosis (hardening and loss of elasticity of the skin) impeded wound healing, and increased potential for infection.
Structure of a Lymph Node
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Lymph, or lymphatic fluid, transports nutrients to tissues and collects tissue wastes.
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Lymph is carried by the lymphatic system, a network of interconnecting vessels.
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The pressure of blood circulating through the capillaries forces lymph out into the tissue spaces.
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This fluid is collected by the lymphatic vessels and eventually returned to the bloodstream through ducts that empty into large veins near the collarbones.
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Lymph is moved by contractions of body muscles, and of the vessels themselves which have valves to prevent backflow.
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Lymph nodes are distributed throughout the system and remove wastes and other particles.
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They also contain large concentrations of white blood cells, which attack invaders such as bacteria and viruses.
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The spleen, thymus, tonsils, and adenoids - all composed of lymphoid tissue - are also part of the immune system.
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Cancer cells that have left their original site travel first to nearby lymph nodes. For this reason, lymph nodes play an important role in the detection and treatment of cancer.
Causes of Lymphedema
Primary lymphedema
Primary lymphedema can be present at birth, or occur during adolescence (praecox) or later in life (tarda). It can be congenital or hereditary and its cause is unknown (idiopathic).
Secondary lymphedema
Secondary lymphedema is more common and can occur following an infection, a traumatic injury, the surgical dissection or resection of the lymph nodes, or as the result of surgery, primarily the excision of malignant tumors, or radiation therapy.
The damage to, or removal of, the lymph nodes can interrupt the normal pathway of the lymphatic fluid, reduce the transport capacity of the lymphatic system, and increase the likelihood of swelling (lymphedema).
Symptoms of Lymphedema
Lymphedema usually begins with swelling in the hands or feet. If you notice persistent swelling in an extremity, it is very important to seek medical advice. If the problem is diagnosed and treatment begins early, the prognosis for improving the condition is much greater than if the swelling is ignored or goes untreated. When lymphedema remains untreated, the limb becomes more swollen (edematous) and the skin hardens and loses elasticity (fibrosis). Moreover, untreated lymphedema leads to infection and sometimes, irreversible complications.
Infection Resulting From Lymphedema
When the lymphatic flow is obstructed, the protein rich lymph fluid accumulates and lays stagnant in the tissues of the limb closest to the obstruction. This creates an environment favorable for the growth of bacteria and ultimately, infection.
The Impact of Lymphedema on the Patient
Lymphedema is a life-long condition, requiring continued and diligent management. If ignored and allowed to advance, it will almost always become steadily worse, more difficult to manage, less likely to return to a less severe stage, and result in conditions that decrease skin integrity, interfere with wound healing and increase the potential for infection. When swelling and inflammation persist, the tissue becomes thick and begins to harden (fibrosis). Consequently, any or all of the following can occur: the limb feels heavy, movement of the limb becomes restricted, joint areas become immobile and ambulation is impaired. Cosmetically, there is the obvious problem of appearance, and there is great difficulty finding clothes and shoes that not only fit, but are unrestrictive as well. As the condition worsens, there are the increased costs associated with medical care, including possible hospitalization. Managing lymphedema may involve some lifestyle changes and a few restrictions, but living a normal, active life is still possible.
Sentinel Node Mapping
The lymphatic system serves as the sewage system for cellular waste in the body. The lymph vessels follow closely beside the blood vessels and receive the cells' waste products. This waste is carried by the lymphatics and is filtered through rounded areas of the lymph system referred to as the lymph nodes.
 Nodes appear as small round capsules and vary in size from several millimeters to several centimeters in diameter. Lymphocytes and monocytes are produced in the nodes and act as filters to stop bacteria, cellular waste and cancer cells to keep them from entering the blood stream. The lymph nodes may also serve as a place where cancer cells set up metastatic sites ( cancer that spreads from the original site to nodes).
Three percent of the lymphatic fluid draining from the breast is found in the lymph nodes located in the area of the breastbone in the internal mammary nodes. Ninety seven percent of the fluid is drained through the nodes located in the area of the armpit, referred to as the axilla.
There are three levels of lymph nodes under the arm. The first level is located from the breast to the underarm area; the second level is behind the pectoralis minor, a small muscle on the chest wall. And the third level is located higher on the chest near the collarbone.
Axillary dissection, which is performed on the majority of patients with invasive carcinoma of the breast, refers to the removal of nodes from different levels of the axilla. The number of nodes vary from person to person. 
Nodes are removed to determine whether cancer has moved from the breast into the node area. This can be of prognostic significance for the patient and will often dictate further management. The term "negative" nodes means that the lymph nodes did not have any evidence of cancer. "Positive" nodes indicates that the cancer was found in the lymph nodes.
A procedure for evaluating lymph node status is "sentinel node mapping". The sentinel node procedure requires the injection of the breast tissue surrounding the cancer site with a small amount of radioactive material just prior to surgery. With time, the radioactive material will migrate to the "sentinel lymph node". This lymph node is found in the operating room using a Geiger Counter. When the sentinel
lymph node is identified and surgically removed, it is then evaluated by the pathologist. This node, the first draining node, is thought to reflect the status of the remainder of the lymph nodes in the axilla. If
it is found to be negative, no further dissection is required.
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