Diseases of the Lymphatic System

The lymphatic system plays many vital roles in the human body, such as immunity, fluid balance, fat and protein absorption, and removal of cellular waste. Lymphatic vessels drain lymphatic fluid from the body’s cells and tissues and carry it to the lymph nodes, where it is assessed by the cells of the immune system. If bacteria, cancer cells, or foreign particles are detected, the lymph nodes swell and become stiff and rubbery due to an accumulation of lymph fluid. A lymphatic disease can also develop in the lymph nodes or other lymphatic tissue.

Please continue reading to learn more about the lymphatic system and some of the conditions that can affect it.

What is the lymphatic system?

The lymphatic system consists of lymph nodes, lymphatic vessels, and lymphatic organs. These lymphatic system components are involved in moving lymphatic fluid or lymph into the bloodstream.

Lymph is a clear, watery fluid. It is the fluid that remains in the body tissues after the arteries, arterioles, and blood capillaries have delivered nutrient-rich blood, and the veins have removed nutrient-poor blood and waste material from tissues throughout the body. The lymphatic system rounds up the excess fluid (lymph) from the body’s tissues, processes it, and ultimately delivers it back to the bloodstream.

What are the components of the lymphatic system?

The lymphatic system has many parts, including:

Lymph or lymphatic fluid

Lymph is the excess fluid that drains from tissues. It contains substances such as fats, proteins, minerals, nutrients, cancer cells, foreign organisms like bacteria and viruses, white blood cells, and other immune system cells.

Lymph Nodes

These are small glands that look like kidney beans. They filter and clean the lymphatic fluid when it passes through them. Lymph nodes also make and store cells of the immune system to fight harmful substances found in the lymph. There are more than 500 lymph nodes distributed throughout the body. They can occur as a solitary lymph node or as a chain of lymph nodes. The neck, armpits, and groin are common locations for regional lymph nodes.

Lymphatic Vessels or Lymphatic Ducts

These are interconnected capillaries (tiny blood vessels or small lymphatic vessels) that carry lymph from the tissues to the lymph nodes and ultimately into large lymphatic vessels known as the collecting ducts. Lymphatic vessels work much like veins and have valves to keep the lymphatic flow moving towards the collecting ducts. There are two collecting ducts in the body, the left and right lymphatic duct (the left lymphatic duct is also called the thoracic duct). The collecting ducts return the lymph to the blood circulation by emptying into the venous circulation, specifically the subclavian veins under the collarbone.

Spleen, Thymus, Tonsils and Adenoids, Bone Marrow, Peyer’s Patches, and Appendix

These lymphatic organs or lymphoid tissue filter lymph, produce and store immune system cells, and fight off foreign organisms and infections. The spleen is the largest lymphatic organ in the body.

Why is the lymphatic system important?

The lymphatic system plays many important functions in the body, such as:

Maintains fluid balance by collecting excess fluid from tissues all over the body and taking it back to the bloodstream. Returning lymph to the circulation helps to maintain normal blood volume and blood pressure and prevents edema (the buildup of excess fluid in the tissues).
Absorbs fats and proteins from the digestive tract and carries it back to the circulatory system through the lymph fluid.
Produces lymphocytes (white blood cells) and other immune cells to fight infection and protect against foreign particles like bacteria and viruses (the lymphatic system is a part of the body’s immune system).
Removes abnormal cells and waste products from the lymph fluid.

What are the common diseases of the lymphatic system?

There are several conditions that can affect the lymph vessels, lymph nodes, and lymphatic organs. The three most common lymphatic diseases include:

Lymphadenopathy and Lymphadenitis

Lymphadenopathy is the medical term for swollen or enlarged lymph nodes. It can occur due to inflammation, infection, or cancer. When the cause of a swollen lymph node is infections or inflammatory disorders, it is called lymphadenitis. For example, strep throat can cause enlargement of regional lymph nodes in the neck. Breast cancer can lead to enlarged lymph nodes in the axillae (armpits).

Lymphedema

This medical term refers to a buildup of lymphatic fluid in the tissues. It most commonly occurs in the arms and legs. Lymphatic system blockages can cause lymphedema due to scar tissue, tumors, or damaged lymph nodes or lymph vessels. Lymphedema can also occur when lymph nodes are surgically removed or subjected to radiation during cancer treatment. Severe lymphedema can be painful, disabling, and disfiguring and can put a person at risk of serious infections.

Lymphatic System Cancers

When lymphocytes (white blood cells) multiply uncontrolled, it can result in a cancer called lymphoma. Two common types of lymphoma are Hodgkin lymphoma and non-Hodgkin lymphoma.

What are some other diseases associated with the lymphatic system?

Some other disorders that can affect the body’s lymphatic system include:

Tonsillitis: An infection and inflammation of the tonsils in the throat.
Lymphangitis: An inflammation of the lymphatic vessels.
Lymphocytosis: The presence of too many white blood cells.
Mesenteric lymphadenitis: An inflammation of lymph nodes in the mesentery (an organ attached to the intestines in the abdomen).
Lymphatic filariasis: A parasitic infection of the lymphatic system that leads to massive swelling in the arms, legs, and genitals.
Intestinal lymphangiectasia: A condition in which lymph is lost in the small intestine, leading to protein loss.
Lymphangioma: A congenital disorder (present from birth) in which there is a malformation of the lymphatic system.
Lymphangiomatosis: A condition characterized by the occurrence of widespread lymphatic vascular malformations.
Castleman Disease: A condition in which there is an overgrowth of lymphatic system cells.
Autoimmune Lymphoproliferative Syndrome: A rare genetic condition associated with an excessive number of white blood cells in the lymph nodes, spleen, and liver.
Lymphangioleiomyomatosis: A rare disorder in which abnormal cells resembling muscle cells grow uncontrolled in the lymph nodes, kidneys, and lungs.

The Takeaway

Lymphatic disorders are frequently diagnosed when lymph nodes become enlarged enough to be palpated (felt) or seen on imaging studies like CT scans or MRIs. Other common symptoms of a lymphatic disorder that warrant evaluation by a healthcare professional include swelling in the arms, legs, or groin; weight loss; fever; and night sweats.

You should know that enlarged lymph nodes are not dangerous in the majority of cases – they are the body's way of fighting an infection. However, significantly enlarged lymph nodes or enlarged lymph nodes in the absence of an infection are problematic and should be examined by a doctor.

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