The lymphatic system is a network of tissues and organs. It is made up of

• Lymph - a fluid that contains white blood cells that defend against germs
• Lymph vessels - vessels that carry lymph throughout your body. They are different from blood vessels.
• Lymph nodes - glands found throughout the lymph vessels. Along with your spleen, these nodes are where white blood cells fight infection.

Your bone marrow and thymus produce the cells in lymph. They are part of the system, too.

The lymphatic system clears away infection and keeps your body fluids in balance. If it's not working properly, fluid builds in your tissues and causes swelling, called lymphedema. Other lymphatic system problems can include infections, blockage, and cancer.

Lymph nodes function to remove debris and pathogens from the lymph, and are thus sometimes referred to as the “filters of the lymph” (Figure). Any bacteria that infect the interstitial fluid are taken up by the lymphatic capillaries and transported to a regional lymph node. Dendritic cells and macrophages within this organ internalize and kill many of the pathogens that pass through, thereby removing them from the body. The lymph node is also the site of adaptive immune responses mediated by T cells, B cells, and accessory cells of the adaptive immune system. Like the thymus, the bean-shaped lymph nodes are surrounded by a tough capsule of connective tissue and are separated into compartments by trabeculae, the extensions of the capsule. In addition to the structure provided by the capsule and trabeculae, the structural support of the lymph node is provided by a series of reticular fibers laid down by fibroblasts.

Lymphedema is the name of a type of swelling. It happens when lymph builds up in your body's soft tissues. Lymph is a fluid that contains white blood cells that defend against germs. It can build up when the lymph system is damaged or blocked. It usually happens in the arms or legs.

Causes of lymphedema include

• Infection
• Cancer
• Scar tissue from radiation therapy or surgical removal of lymph nodes
• Inherited conditions in which lymph nodes or vessels are absent or abnormal

Treatment can help control symptoms. It includes exercise, compression devices, skin care, and massage.

Lymphedema is the build-up of fluid in soft body tissues when the lymph system is damaged or blocked.

Lymphedema occurs when the lymph system is damaged or blocked. Fluid builds up in soft body tissues and causes swelling. It is a common problem that may be caused by cancer and cancer treatment. Lymphedema usually affects an arm or leg, but it can also affect other parts of the body. Lymphedema can cause long-term physical, psychological, and social problems for patients.

The lymph system is a network of lymph vessels, tissues, and organs that carry lymph throughout the body.

The parts of the lymph system that play a direct part in lymphedema include the following:

• Lymph: Colorless, watery fluid that travels through the lymph vessels and carries T and B lymphocytes. Lymphocytes are a type of white blood cell.
• Lymph vessels: A network of thin tubes that collect lymph from different parts of the body and return it to the bloodstream.
• Lymph nodes: Small, bean-shaped structures that filter lymph and store white blood cells that help fight infection and disease. Lymph nodes are found along a network of lymph vessels throughout the body. Groups of lymph nodes are found in the neck, underarm, mediastinum, abdomen, pelvis, and groin.

The spleen, thymus, tonsils, and bone marrow are also part of the lymph system but do not play a direct part in lymphedema.

Lymphedema occurs when lymph is not able to flow through the body the way that it should.

When the lymph system is working as it should, lymph flows through the body and is returned to the bloodstream.

• Fluid and plasma leak out of the capillaries (smallest blood vessels) and flow around body tissues so the cells can take up nutrients and oxygen.
• Some of this fluid goes back into the bloodstream. The rest of the fluid enters the lymph system through tiny lymph vessels. These lymph vessels pick up the lymph and move it toward the heart. The lymph is slowly moved through larger and larger lymph vessels and passes through lymph nodes where waste is filtered from the lymph.
• The lymph keeps moving through the lymph system and collects near the neck, then flows into one of two large ducts:
  • The right lymph duct collects lymph from the right arm and the right side of the head and chest.
  • The left lymph duct collects lymph from both legs, the left arm, and the left side of the head and chest.
• These large ducts empty into veins under the collarbones, which carry the lymph to the heart, where it is returned to the bloodstream.

When part of the lymph system is damaged or blocked, fluid cannot drain from nearby body tissues. Fluid builds up in the tissues and causes swelling.

There are two types of lymphedema.

Lymphedema may be either primary or secondary:

• Primary lymphedema is caused by the abnormal development of the lymph system. Symptoms may occur at birth or later in life.
• Secondary lymphedema is caused by damage to the lymph system. The lymph system may be damaged or blocked by infection, injury, cancer, removal of lymph nodes, radiation to the affected area, or scar tissue from radiation therapy or surgery.

If you have breast cancer, no matter which type of surgery you have, you will likely have one or more lymph nodes removed from under your arm. This is not the case if you have DCIS, since cells in DCIS will not travel to other parts of the body.

Lymph nodes are part of the immune system, which protects your body against infection and disease. Lymph nodes are small, round organs that are clustered in many areas of the body, such as the underarm. They are connected to one another by lymph vessels, which carry a clear fluid, called lymph. Cancer cells can spread to lymph nodes and other parts of the body through lymph vessels.

Once lymph nodes are removed, they will be checked for cancer. Knowing whether cancer is in the underarm lymph nodes can help the doctor decide if you need any treatment in addition to surgery. And, if so, what type you might need.

Lymphedema is swelling caused by a build-up of lymph. You may have this type of swelling in the hand, arm, chest, or back on the side of your body where lymph nodes were removed by breast cancer surgery or damaged by radiation therapy.

Some important facts to know about lymphedema are:

• Lymphedema can show up soon after surgery.
• Sometimes, lymphedema can last for years.
• Lymphedema can show up months or years after cancer treatment is over.
• Lymphedema might develop after an insect bite, minor injury, or burn on the arm where lymph nodes were removed or damaged.
• Lymphedema can cause pain and other problems. To help with these problems, some people find it helpful to work with a physical therapist or doctor who specializes in rehabilitation and has special lymphedema training.

Sentinel Lymph Node Biopsy is a type of surgery in which the surgeon removes a few lymph nodes for testing. First, the surgeon injects a dye, a radioactive tracer, or both into the breast near the tumor. This helps the surgeon see which lymph nodes the lymph from that area of the breast flows to first. Then, he or she removes the node or nodes that contain the dye or radioactive tracer to see if they have cancer. If they do not contain cancer, it is not likely that the other nodes under the arm have cancer. This means that the surgeon usually doesn’t have to remove any other lymph nodes.

Fewer lymph nodes are removed with sentinel lymph node biopsy than with standard lymph node surgery. Having fewer lymph nodes removed helps lower the chances that you will develop lymphedema and other problems caused by damage to lymph vessels and lymph nodes.

Lymphedema is a condition in which the lymph fluid does not drain properly. It may build up in the tissues and causes swelling. This can happen when part of the lymph system is damaged or blocked, such as during surgery to remove lymph nodes, or radiation therapy. Cancers that block lymph vessels can also cause lymphedema.

Lymphedema usually affects an arm or leg, but it can also affect other parts of the body, such as the head and neck. You may notice symptoms of lymphedema at the part of your body where you had surgery or received radiation therapy. Swelling usually develops slowly, over time. It may develop during treatment or it may start years after treatment.

At first, lymphedema in an arm or leg may cause symptoms such as:

• swelling and a heavy or achy feeling in your arms or legs that may spread to your fingers and toes
• a dent when you press on the swollen area
• swelling that is soft to the touch and is usually not painful at first

Lymphedema that is not controlled may cause:

• more swelling, weakness, and difficulty moving your arm or leg
• itchy, red, warm skin, and sometimes a rash
• wounds that don’t heal, and an increased risk of skin infections that may cause pain, redness, and swelling
• thickening or hardening of the skin
• tight feeling in the skin; pressing on the swollen area does not leave a dent
• hair loss

Lymphedema in the head or neck may cause:

• swelling and a tight uncomfortable feeling on your face, neck, or under your chin
• difficulty moving your head or neck

Tell your health care team as soon as you notice symptoms. Early treatment may prevent or reduce the severity of problems caused by lymphedema.

Ways to Manage Lymphedema

Steps you may be advised to take to prevent lymphedema or to keep it from getting worse:

• Protect your skin. Use lotion to avoid dry skin. Use sunscreen. Wear plastic gloves with cotton lining when working in order to prevent scratches, cuts, or burns. Keep your feet clean and dry. Keep your nails clean and short to prevent ingrown nails and infection. Avoid tight shoes and tight jewelry.
• Exercise. Work to keep body fluids moving, especially in places where lymphedema has developed. Start with gentle exercises that help you to move and contract your muscles. Ask your doctor or nurse what exercises are best for you.
• Manual lymph drainage. See a trained specialist (a certified lymphedema therapist) to receive a type of therapeutic massage called manual lymph drainage. Therapeutic massage works best to lower lymphedema when given early, before symptoms progress.

Ways to Treat Lymphedema

Your doctor or nurse may advise you to take these and other steps to treat lymphedema:

• Wear compression garments or bandages. Wear special garments, such as sleeves, stockings, bras, compression shorts, gloves, bandages, and face or neck compression wear. Some garments are meant to be worn during the day, while others are to be worn at night.
• Other practices. Your health care team may advise you to use compression devices (special pumps that apply pressure periodically) or have laser therapy or other treatments.

Talking With Your Health Care Team about Lymphedema

Prepare for your visit by making a list of questions to ask. Consider adding these questions to your list:

• What can I do to prevent these problems?
• What symptoms should I call you about?
• What steps can I take to feel better?
• Would you recommend that I see a certified lymphedema therapist?
• If lymphedema advances, what special garments should I wear during the day? During the night?

Lymphoma is a general term for cancers that start in the lymph system (the tissues and organs that produce, store, and carry white blood cells that fight infections). The two main kinds of lymphoma are—

• Hodgkin lymphoma, which spreads in an orderly manner from one group of lymph nodes to another.
• Non-Hodgkin lymphoma, which spreads through the lymphatic system in a non-orderly manner.

Hodgkin lymphoma and non-Hodgkin lymphoma can occur in children, teens, and adults.

What Causes Lymphoma?

Non-Hodgkin lymphoma becomes more common as people get older. Unlike most cancers, rates of Hodgkin lymphoma are highest among teens and young adults (ages 15 to 39 years) and again among older adults (ages 75 years or older). White people are more likely than black people to develop non-Hodgkin lymphoma, and men are more likely than women to develop lymphoma.

Scientists do not fully understand all of the causes of lymphoma, but research has found many links. For example—

• Research has shown that people who are infected with the human immunodeficiency virus (HIV) are at much higher risk of developing lymphoma.
• Other viruses, such as human T-cell lymphotrophic virus and Epstein Barr virus, also have been linked with certain kinds of lymphoma.
• People exposed to high levels of ionizing radiation have a higher risk of developing non-Hodgkin lymphoma.
• Family history has been linked with a higher risk of Hodgkin lymphoma.
• Some studies suggest that specific ingredients in herbicides and pesticides may be linked with lymphoma, but scientists don’t know how much is needed to raise the risk of developing lymphoma.

Symptoms of Lymphoma

Symptoms of Hodgkin lymphoma and non-Hodgkin lymphoma include swollen lymph nodes, especially in the part of the body where the lymphoma starts to grow. Other symptoms include fever, night sweats, feeling tired, and weight loss.

These symptoms can also come from other conditions. If you have any of them, talk to your doctor.

What is Hodgkin lymphoma?

Hodgkin lymphoma, also called Hodgkin disease, is a type of cancer that develops in the lymph system. Your lymph system is part of your immune system. It helps protect your body from infection and disease.

The lymph system is made up of tissues and organs that produce, store, and carry white blood cells. It includes your:

• Bone marrow
• Lymph nodes
• Lymphatic vessels
• Spleen
• Thymus
• Tonsils

Hodgkin lymphoma is one of the main types of lymphoma. The other is non-Hodgkin lymphoma. Each type starts in different types of white blood cells.

What causes Hodgkin lymphoma?

The cause of Hodgkin lymphoma is unknown. But there are certain people who are at higher risk of developing it.

Who is more likely to develop Hodgkin lymphoma?

Certain factors can make you more likely to develop Hodgkin lymphoma:

• Age. Hodgkin lymphoma is most common in early adulthood (age 20-39 years) and in late adulthood (age 65 years and older).
• Being male. The risk of adult Hodgkin lymphoma is slightly higher in males than in females.
• Past Epstein-Barr virus (EBV) infection. Having an infection with EBV as a young child or teenager increases your risk of Hodgkin lymphoma.
• A family history of Hodgkin lymphoma. Having a parent or sibling with Hodgkin lymphoma increases your risk of developing it.

What are the symptoms of Hodgkin lymphoma?

The signs and symptoms of Hodgkin lymphoma may include:

• Painless, swollen lymph nodes in the neck, underarm, or groin
• Fever for no known reason
• Drenching night sweats (very heavy sweating during sleep)
• Weight loss for no known reason in the past 6 months
• Itchy skin, especially after bathing or drinking alcohol
• Fatigue

How is Hodgkin lymphoma diagnosed?

To find out if you have Hodgkin lymphoma, your provider:

• Will ask about your symptoms and medical history. This will include checking for signs of disease, such as lumps or anything else that seems unusual.
• May order some lab tests, such as:
  • Complete blood count
  • Blood chemistry studies
  • Lactate dehydrogenase (LDH) test
  • Erythrocyte sedimentation rate (ESR) test
  • Blood tests to rule out other medical conditions
  • May do imaging tests such as a CT and PET (positron emission tomography) scans
  • May do a lymph node biopsy

What are the treatments for Hodgkin lymphoma?

Treatments for Hodgkin lymphoma include:

• Chemotherapy
• Radiation therapy
• Targeted therapy, which uses drugs or other substances that attack specific cancer cells with less harm to normal cells
• Cancer immunotherapy

Hodgkin lymphoma can usually be cured if it is found and treated early.

Your spleen is an organ above your stomach and under your ribs on your left side. It is about as big as your fist. The spleen is part of your lymphatic system, which fights infection and keeps your body fluids in balance. It contains white blood cells that fight germs. Your spleen also helps control the amount of blood in your body, and destroys old and damaged cells.

Certain diseases might cause your spleen to swell. You can also damage or rupture your spleen in an injury, especially if it is already swollen. If your spleen is too damaged, you might need surgery to remove it. You can live without a spleen. Other organs, such as your liver, will take over some of the spleen's work. Without a spleen, however, your body will lose some of its ability to fight infections.

Spleen is a secondary lymphoid organ that filters pathogens from the blood (white pulp) and removes degenerating or damaged blood cells (red pulp).

In addition to the lymph nodes, the spleen is a major secondary lymphoid organ (Figure). It is about 12 cm (5 in) long and is attached to the lateral border of the stomach via the gastrosplenic ligament. The spleen is a fragile organ without a strong capsule, and is dark red due to its extensive vascularization. The spleen is sometimes called the "filter of the blood" because of its extensive vascularization and the presence of macrophages and dendritic cells that remove microbes and other materials from the blood, including dying red blood cells. The spleen also functions as the location of immune responses to blood-borne pathogens.

Spleen

(a) The spleen is attached to the stomach. (b) A micrograph of spleen tissue shows the germinal center. The marginal zone is the region between the red pulp and white pulp, which sequesters particulate antigens from the circulation and presents these antigens to lymphocytes in the white pulp. EM × 660. (Micrograph provided by the Regents of the University of Michigan Medical School © 2012)

The spleen is also divided by trabeculae of connective tissue, and within each splenic nodule is an area of red pulp, consisting of mostly red blood cells, and white pulp, which resembles the lymphoid follicles of the lymph nodes. Upon entering the spleen, the splenic artery splits into several arterioles (surrounded by white pulp) and eventually into sinusoids. Blood from the capillaries subsequently collects in the venous sinuses and leaves via the splenic vein. The red pulp consists of reticular fibers with fixed macrophages attached, free macrophages, and all of the other cells typical of the blood, including some lymphocytes. The white pulp surrounds a central arteriole and consists of germinal centers of dividing B cells surrounded by T cells and accessory cells, including macrophages and dendritic cells. Thus, the red pulp primarily functions as a filtration system of the blood, using cells of the relatively nonspecific immune response, and white pulp is where adaptive T and B cell responses are mounted.

The spleen is located in the upper left abdominal cavity, just beneath the diaphragm, and posterior to the stomach. It is similar to a lymph node in shape and structure but it is much larger. The spleen is the largest lymphatic organ in the body. Surrounded by a connective tissue capsule, which extends inward to divide the organ into lobules, the spleen consists of two types of tissue called white pulp and red pulp. The white pulp is lymphatic tissue consisting mainly of lymphocytes around arteries. The red pulp consists of venous sinuses filled with blood and cords of lymphatic cells, such as lymphocytes and macrophages. Blood enters the spleen through the splenic artery, moves through the sinuses where it is filtered, then leaves through the splenic vein.

The spleen filters blood in much the way that the lymph nodes filter lymph. Lymphocytes in the spleen react to pathogens in the blood and attempt to destroy them. Macrophages then engulf the resulting debris, the damaged cells, and the other large particles. The spleen, along with the liver, removes old and damaged erythrocytes from the circulating blood. Like other lymphatic tissue, it produces lymphocytes, especially in response to invading pathogens. The sinuses in the spleen are a reservoir for blood. In emergencies such as hemorrhage, smooth muscle in the vessel walls and in the capsule of the spleen contracts. This squeezes the blood out of the spleen into the general circulation.

Vaccines are especially critical for people with chronic health conditions such as asplenia.

If you do not have a spleen or your spleen does not work well, talk with your doctor about:

• Influenza vaccine each year to protect against seasonal flu
• Tdap vaccine to protect against whooping cough and tetanus
• Hib vaccine to protect against Haemophilus influenzae type b (Hib) if you were not previously vaccinated with the vaccine
• Pneumococcal vaccines (both types) to protect against pneumonia and other pneumococcal disease
• Meningococcal vaccines (both types) to protect against meningitis and other meningococcal disease
• Zoster vaccine to protect against shingles if you are 60 years and older
• HPV vaccine series to protect against human papillomavirus if you are a man up to age 21 or woman up to age 26
• MMR vaccine to protect against measles, mumps, and rubella if you were born in 1957 or after and have not gotten this vaccine or do not have immunity to these diseases
• Varicella vaccine to protect against chickenpox if you were born in 1980 or after and have not gotten two doses of this vaccine or do not have immunity to this disease

Castleman disease (CD) is a rare condition that affects the lymph nodes and related tissues. There are two main forms: unicentric CD and multicentric CD. Unicentric CD is a "localized" condition that is generally confined to a single set of lymph nodes, while multicentric CD is a "systemic" disease that affects multiple sets of lymph nodes and other tissues throughout the body. The exact underlying cause of CD is currently unknown; however, it is thought to occur sporadically in people with no family history of the condition. Treatment varies based on the form of the condition, the severity of symptoms and whether or not the affected person also has an HIV and/or human herpes virus type 8 (HHV-8) infection.

Multicentric Castleman disease (MCD) is a rare disease that affects the lymph nodes and related tissues. It is a form of Castleman disease that is "systemic" and involves multiple regions of lymph nodes (as opposed to unicentric Castleman disease, which involves a single lymph node or single region of lymph nodes).

The signs and symptoms of MCD are often nonspecific, and are mild in some people but life-threatening in others. Symptoms may include enlarged lymph nodes in multiple regions, fever, weight loss, nausea, rash, and/or an enlarged large liver and spleen. The disease is diagnosed based on the symptoms present, laboratory test results, imaging studies, and results of a biopsy of the lymph nodes which shows specific features when studied under the microscope.

In some cases, MCD is caused by human herpesvirus-8 (HHV-8) and is referred to as HHV-8-associated MCD. In other cases, the cause is not known and it is referred to as HHV-8 negative MCD, or idiopathic MCD (iMCD). Treatment of MCD is challenging, and treatment options and outcomes depend on the type and severity in each person.

A sentinel lymph node biopsy (SLNB) is a procedure in which the sentinel lymph node is identified, removed, and examined to determine whether cancer cells are present. It is used in people who have already been diagnosed with cancer.

A negative SLNB result suggests that cancer has not yet spread to nearby lymph nodes or other organs.

A positive SLNB result indicates that cancer is present in the sentinel lymph node and that it may have spread to other nearby lymph nodes (called regional lymph nodes) and, possibly, other organs. This information can help a doctor determine the stage of the cancer (extent of the disease within the body) and develop an appropriate treatment plan.

Lymphatic filariasis (LF) is a neglected tropical disease (NTD) caused by microscopic, thread-like worms. The adult worms only live in the human lymph system, which maintains the body’s fluid balance and fights infections. LF is spread from person to person by mosquitoes. People with LF can suffer severe and even permanent disability. Affected people frequently are unable to work because of their disability, and this harms their families and their communities. LF affects over 120 million people in 72 countries worldwide. You cannot get infected with the worms in the continental United States.

Key Facts

• Lymphatic filariasis (LF) is a parasitic disease caused by three species of microscopic, thread-like worms.
• The disease spreads from person to person by mosquito bites.
• If you live in or travel to an area with lymphatic filariasis, avoiding mosquito bites is the best way to prevent it.
• LF is considered a neglected tropical disease because it causes substantial illness for more than 1 billion people globally.
• Neglected tropical diseases are infectious diseases that cause devastating illness for more than 120 million people.

The Impact of NTDs

Neglected tropical diseases (NTDs) are a group of parasitic and bacterial diseases that cause substantial illness for more than one billion people globally. Affecting the world’s poorest people, NTDs impair physical and cognitive development, contribute to mother and child illness and death, and make it difficult to earn a living.

LF’s Devastation

Lymphatic filariasis is a leading cause of permanent disability worldwide. Communities frequently shun and reject women and men disfigured by the disease. Affected people frequently are unable to work because of their disability, and this harms their families and their communities.

Treatment for LF

Experts believe that lymphatic filariasis can be eliminated globally. The elimination strategy is based on annual treatment of whole communities with combinations of drugs that kill the microscopic worms. Hundreds of millions of people are being treated each year.

The Impact of NTDs

Neglected tropical diseases (NTDs) are a group of parasitic and bacterial diseases that cause substantial illness for more than one billion people globally. Affecting the world’s poorest people, NTDs impair physical and cognitive development, contribute to mother and child illness and death, and make it difficult to earn a living.

Prevention Tips

Avoiding mosquito bites is best. People who live in or travel to an area with lymphatic filariasis should also:

• Sleep under a mosquito net
• Wear long sleeves and trousers
• Use mosquito repellent on exposed skin between dusk and dawn.