Lymphoedema - Causes of lymphoedema

There are two types of lymphoedema, called primary and secondary lymphoedema, which have different causes.

The main causes of primary and secondary lymphoedema are outlined below.

Primary lymphoedema

Primary lymphoedema is caused by alterations (known as mutations) in genes responsible for the development of the lymphatic system (a network of channels and glands distributed throughout the body that help fight infection and remove excess fluid from the body).

These "faulty" genes result in the parts of the lymphatic system responsible for draining fluid not developing properly or not working as they should.

Primary lymphoedema usually runs in families, but not every child born to someone with the condition will develop it themselves. 

Secondary lymphoedema

Secondary lymphoedema develops in people who previously had a normal lymphatic system.

It can have a number of different causes. Some of the most common causes are explained below.

Surgical treatment of cancer

Cancer cells can spread around the body through the lymphatic system, so part of the treatment for the condition can involve surgically removing sections of the lymphatic system potentially containing cancerous cells.

Although the surgeon will try to ensure limited damage to your lymphatic system, this isn't always possible.

There is a particular risk of lymphoedema occurring as a complication of treatment for:

• breast cancer
• melanoma skin cancer
• gynaecological cancers – such as cervical cancer and vulval cancer
• genitourinary cancers – such as prostate cancer or penile cancer

Radiotherapy

Radiotherapy uses controlled doses of high-energy radiation to destroy cancerous tissue, but it can also damage healthy tissue.

If it's necessary to use radiotherapy to destroy cancerous cells in your lymphatic system, there is a risk that the system could become permanently damaged and unable to drain fluid properly.

Infections

In some cases, an infection can cause lymphoedema.

Cellulitis is a bacterial skin infection that can cause lymphoedema. Severe cellulitis can damage the tissue around the lymphatic system, causing it to become scarred.

Another infectious cause of lymphoedema is a parasitic infection called filariasis. This is a common cause of lymphoedema worldwide, but is not a risk in the UK.

Inflammation

Conditions that cause tissue to become inflamed (red and swollen) can also permanently damage the lymphatic system. Medical conditions that can cause lymphoedema include:

• rheumatoid arthritis – which causes pain and swelling in the joints
• eczema – which causes the skin to become itchy, reddened, dry and cracked

Venous diseases 

Venous diseases, which affect the flow of blood through the veins, can cause lymphoedema in some people. The abnormal or damaged veins can result in excessive fluid leaking from the blood into the tissue spaces. This overwhelms and eventually exhausts the parts of the lymphatic system responsible for draining this fluid.

Some venous diseases that can lead to lymphoedema include:

• deep vein thrombosis (DVT) – a blood clot in one of the deep veins in the body
• varicose veins (swollen and enlarged veins) – where poor drainage of blood in the veins causes higher vein pressure, and more fluid passes into the surrounding tissues

Obesity

People who are obese, particularly those who are severely obese, have an increased risk of developing lymphoedema. It’s not clear exactly why this is, but it has been suggested that the extra fatty tissue affects the lymphatic channels in some way, reducing the flow of fluid through them.

In these cases, weight loss is an important part of treatment and even just starting to lose weight can make a big difference.

Trauma and injury

In a small number of cases, lymphoedema can be caused by an accidental injury to the lymphatic system. For example, lymphoedema can sometimes occur after extensive soft tissue loss or bruising.

Immobility

Movement and exercise helps lymph drainage, as muscle activity surrounding the lymphatic vessels massages fluid into and along them. Therefore, reduced movement can lead to lymphoedema, because the fluid in the lymphatic system does not get moved on, causing swelling.

For example, people who are unable to move fully for a long time due to an illness or surgery may be at risk of lymphoedema.