Lymphoedema is a chronic condition that causes swelling in the body's tissue.
Lymphoedema is defined as the excessive accumulation of tissue fluid, or ‘lymph’ that results from impaired lymphatic drainage. The term ‘lymphoedema’ should be confined to describing oedema in patients in which a lymphatic abnormality has been confirmed.
Lymphoedema principally involves the legs (80%), although the arms, genitalia and face can also be affected. It can affect anyone, at any age and although it’s not life-threatening, it can be very distressing and can become a major physical and social problem for sufferers. It is thought to affect around 500 million people worldwide and about 2% of the population in the United Kingdom.
In most cases the onset of lymphoedema is insidious, however it can also be quite sudden. Many patients say that they had very mild or no swelling initially, but that some trauma, such as a twisted ankle, minor infection or insect bite, precipitated a rapid progression of lymphoedema.
There is no cure for lymphoedema at present, but with appropriate treatment and patient co-operation, it can be very well managed and kept under control.
In most cases the cause of lymphoedema is damage to the lymphatic vessels which can follow surgical procedures, radiotherapy or other conditions such as certain infections. This type of lymphoedema is termed ‘secondary’ lymphoedema.
In some cases there is no obvious cause and the lymphoedema has developed because of an abnormality of the lymphatic vessels. Sometimes, the swelling is present at birth but in many cases the swelling does not develop until later life. This form of lymphoedema is known as ‘primary’ lymphoedema.
A number of different types of abnormality of the lymphatic vessels can cause lymphoedema.
First of all, the lymphatic channels may be absent (aplasia). Sometimes the lymphatics are few in number (hypoplasia). There may be an excessive number of abnormally functioning lymphatics (numerical hyperplasia) or there may be dilated vessels (megalymphatics) which are often associated with lymphatic fluid collections or leaks such as chylothorax (lymph in the chest), chylous ascites (lymph collection in the abdomen).
Rarely, the lymph can actually leak out of vesicles or ‘blisters’ on the skin, mucous membranes or bowel.
Finally, the lymphatics may be obstructed secondary to an inflammatory-type process in the lymph nodes draining an area of the body. This causes the lymph flow to be slowed or halted, which can then cause lymphoedema.
Before the diagnosis of lymphoedema is made, other causes of swelling (oedema) must be excluded. These include:
An important cause of swelling is an abnormality of the veins. In lipodystrophy, there is an abnormality of subcutaneous fat deposition and this is frequently misdiagnosed as lymphoedema. In some cases it is important to make sure that the swelling is not a result of a tumour or mass obstructing the lymphatics, hence why lymphoedema isn’t always diagnosed instantly.
Because the tissue fluid is not being cleared normally, any bacteria which get into the skin or subcutaneous tissues from a minor trauma or scratch are more likely to cause an infection. The infection which results is called cellulitis. It is unfortunate that with each episode of cellulitis lymphatic vessels are damaged further. Avoidance of infections is therefore very important.
Very rarely after many years of lymphoedema, a malignant tumour of the lymph vessels can occur.
These are tiny vessels, which, under normal circumstances, remove the tissue fluid that is constantly leaking out of the other small blood vessels, and return it back into the circulation. Lymph is collected from the arms, legs, trunk and body cavities by a complex network of lymphatics and is returned back into the circulation via a larger lymphatic (the thoracic duct) in the base of the neck.