Fluid circulates through the circulatory system to deliver nutrients and cells through the human body. Different names are given to body fluids based on where they are found:
- Blood is fluid inside blood vessels.
- Lymph is fluid inside lymph vessels.
- Tissue fluid (also known as interstitial fluid) is fluid sitting in the tissue spaces.
The circulatory system of the human body involves both the cardiovascular (blood) and the lymphatic (lymph) systems working together.
Image shows how the circulatory system and the lymphatic system together form the circulatory system.
What is lymphoedema?
Lymphoedema (also spelled lymphedema) is from the latin word “lympha” which means “pure water or streams”. This name fits with the fact that lymph is clear and that the lymphatic system filters tissue fluid through lymph nodes – lymph organs designed to keep the body free from infection and disease. “Oedema” refers to conditions where there is an excess of watery fluid collecting in the body.
Lymphoedema is therefore where excess lymph fluid from the lymphatic system collects in the body – usually resulting in swelling.
What is lymph?
Lymph simply refers to the fluid found in the lymphatic system and lymph vessels of the body.
There are two types of lymph fluid in the human body:
1. Lymph fluid that does not contain fat.
This type of fluid is clear. It is found inside most superficial lymph vessels such as in the tissues of the arms, legs, breast, genitals and face. You will have seen lymph if you have ever seen fluid inside a large blister. The fluid that collects under the skin in a blister is clear. At this stage the fluid is tissue fluid as it has not been collected by the lymph vessels. In order for the fluid in the blister to escape it must be carried by the lymph vessels or alternatively it can escape through the skin, which is not ideal as the skin will be broken leaving it susceptible to infection.
Image of a common blister by Frazzmatazz, CC BY-SA 3.0, via Wikimedia Commons.
2. Lymph fluid that contains fat.
This type of lymph is known as chyle. Chyle is found in the lymphatics of the digestive system which drain into the large lymphatics of the abdomen. The cisterna chyli is the most lower part of the thoracic duct – the biggest lymphatic vessel in the human body. This lymph vessel receives fatty chyle from the intestines and contributes to digestion via the transportation of fats within the human body.
It is the first type of non-fatty lymph fluid that causes the swelling most commonly seen in those living with lymphoedema and can result in swelling in the arms, legs, breast, genitals and face.
What causes lymphoedema?
Lymphoedema may arise because lymph vessels or lymph nodes have been damaged or were not formed correctly.
Primary lymphoedema means that there is a problem with either the functioning of the lymphatic system (e.g. slow intrinsic pumping of lymphangions, parts of lymph vessels known as the lymph collectors) or the formation of the lymphatic system (e.g. decreased number of lymph nodes in a given area).
There may be hypoplasia of lymphatic vessels (a reduced number of lymphatic vessels), hyperplasia of lymphatic vessels (vessels that are too large to be functional) or aplasia (absence) of some part of the lymphatic system. An abnormality in the lymphatic system may be present at birth (congenital), develop at the onset of puberty (praecox), or not become apparent for many years into adulthood (tarda) and may or may not be associated with other congenital abnormalities/syndromes.
Secondary lymphoedema is the most common type of lymphoedema which develops following damage to the lymphatic system.
The damage may occur as a result of some cancer treatments including the removal of lymph nodes, following radiotherapy to lymph node groups or with the progression of malignant disease. The onset of lymphoedema may be at any time. It may occur within months of the damage or it may appear years later.
Secondary lymphoedema may also arise without a cancer diagnosis when one or more of the following conditions occur:
- Trauma and tissue damage such as burns or surgery
- Venous disease
- Immobility (also known as lack of movement), dependency (also known as legs or arms hanging downwards and gravity impacting them) or obesity
- Infection such as cellulitis
- Filariasis – worms that invade the lymphatic system. Lymphatic filariasis is a major cause of lymphoedema in the sub-tropical areas of the world whereby parasitic filarial worms are transmitted through mosquito bites. The parasites lodge in the lymphatic system causing destruction of the healthy vessels and nodes, resulting in lymphoedema.
Primary and secondary lymphoedema can also occur together. An example of this would be a person who is born with a decreased number of lymph nodes in their legs resulting in primary lymphoedema of the legs. They then develop left-sided breast cancer and have arm lymph nodes removed from the left arm. This then results in secondary left side breast cancer-related lymphoedema.
In the video below Professor Neil Piller (Lymphologist from Flinders University) talks about the two types of lymphoedema.
What is the difference between primary and secondary lymphoedema? (Transcription)
There are two types of lymphoedema – a primary lymphedema and a secondary lymphedema.
Primary lymphedema is basically a consequence of some mis-formation or a malformation of our lymphatic vessels and this means that the lymphatic vessels may not be able to pump as hard as they can, or should be able to pump normally, or in some primary lymphoedemas; they may not have as many lymphatic vessels as a person needs. In some primary lymphoedemas, also those vessels are in the wrong spot.
Primary lymphoedemas are a consequence of misreading of genetic information and these primary lymphoedemas are of three types, one, which seems to appear around birth, one which appears generally about puberty and one which generally appears about the age of 30, but in a way it’s all a continuum. Basically primary lymphoedemas are associated with a malformation of the lymphatic system and an inability to deal with the load on that lymphatic system. That primary malformation (problem) may be:-
- not enough lymphatic vessels
- lymphatic vessels in the wrong spot
- or lymphatic vessels that don’t pump correctly and are therefore not as strong as they should be.
Then we have another form of lymphedema called secondary lymphoedema.
Secondary lymphoedema occurs when the lymphatic system has been damaged or destroyed by surgery by radiotherapy, by fibrosis, by tissue damage and these sorts of things. Many primary lymphoedemas underlie secondary lymphoedema, which is a very interesting idea because sometimes a person will develop a secondary lymphoedema surprisingly, when they’ve just had one or two lymph nodes taken out and if you have a look at these people, they’ve got a lymphatic system which is not normal, which has got a primary abnormality to it, which is not strong in its ability to pump or isn’t as dense as it should be in terms of the location of the major vessels of the lymphatic system.
So a primary lymphoedema, may underlie many secondary lymphoedemas.
What are the consequences of lymphoedema?
There are three main consequences of lymphoedema affecting the tissues:
FLUID: Tissues become swollen as tissue fluid accumulates without the lymphatic system being able to drain this fluid away. As lymphoedema persists overtime (known as chronic lymphoedema) the tissues become inflamed and this places patients at risk of serious skin infections known as cellulitis.
FIBROSIS: Tissues become ‘fibrosed’ in chronic lymphoedema, which means they may become thickened, hardened or turn into a special type of “scar tissue.”
FAT: Tissues become fatty in chronic lymphoedema. Fatty tissue can become so severe that liposuction can sometimes be warranted to remove litres of accumulated fat. The liposuction does not cure the lymphoedema, but it removes the excessive fatty tissue so that the body area becomes easier to move.
Lymphoedema involves tissue inflammation through the process of fluid, fibrosis and fatty tissue infiltrating the tissues. As such the condition should not be ignored. Early treatment has been shown to get the best results.
Lymphoedema is a condition involving long-term tissue swelling that occurs when the lymphatic system fails to work properly. Without the lymphatic system functioning correctly, lymph vessels in a given body area aren’t able to collect tissue fluid, so tissue fluid builds up and swelling occurs. Over time the fluid build up can become fibrosed and then fatty. If left untreated, swelling as a result of tissue fluid build up can become irreversible and is known as chronic lymphoedema. Education and early detection are the best ways to avoid life-long consequences and symptoms of lymphoedema.
You can find out more about early detection of lymphoedema in our CANdetect course, designed for those at risk of developing lymphoedema. For those who have already been diagnosed with lymphoedema and want to find out more about successfully managing their condition and symptoms, we have created CANmanage.