The causes of lymphoedema come from damage or disruption to the lymphatic system. This system is responsible for collecting and returning lymph — a fluid rich in protein — back to the bloodstream. When it no longer works properly, fluid builds up in body tissues, leading to chronic swelling. The most common areas affected are the arms or legs.
There are two main categories for the causes of lymphoedema: primary lymphoedema and secondary lymphoedema. While the origins are different, both types result in poor lymph drainage and fluid retention.
Primary Lymphoedema (Congenital or Inherited)
Primary lymphoedema happens due to abnormalities in the lymphatic system’s development. It may appear at birth, during puberty, or in adulthood. Although it is rare, it often runs in families and may involve genetic mutations.
Common causes of primary lymphoedema include:
- Milroy disease (congenital lymphoedema): This begins at or shortly after birth and is linked to mutations in the FLT4 gene, which controls lymph vessel growth.
- Meige disease (lymphoedema praecox): This starts around puberty and is the most frequent form of primary lymphoedema.
- Lymphoedema tarda: Symptoms appear after age 35 without a clear cause. It may result from poorly developed or faulty lymph vessels.
In all cases, the lymph vessels may be too small, missing, or not functioning properly, which leads to fluid build-up over time.
Secondary Lymphoedema (Acquired)
Secondary lymphoedema is more common and results from damage to the lymphatic system. This damage is usually caused by a separate medical issue, treatment, or injury.
The most common causes of secondary lymphoedema include:
a) Cancer Treatment
Cancer-related procedures are a leading cause of lymphoedema. These include:
- Lymph node removal: Common during breast, prostate, or pelvic cancer surgery
- Radiation therapy: Radiation can scar or block lymph vessels
- Tumour growth: A tumour may block or press on lymphatic pathways
b) Infection
Infections can directly damage lymph vessels. In tropical regions, filariasis, a parasitic disease caused by mosquito-borne worms, is a major cause of lymphoedema. In other settings, cellulitis — a recurring bacterial skin infection — can scar lymphatic tissues and worsen swelling.
c) Injury or Surgery
Accidents or surgical trauma to the lymphatic system may also trigger swelling. Burns, cuts, or blunt injuries can disrupt drainage pathways. Even surgeries not related to cancer can put someone at risk.
d) Chronic Venous Insufficiency
When veins fail to return blood properly from the lower legs, pressure builds up. This forces fluid into the surrounding tissues. Over time, the lymphatic system becomes overwhelmed, leading to combined venous and lymphatic swelling.
e) Obesity
Excess weight compresses lymph vessels and increases inflammation, especially in the lower limbs. Severe obesity is now a recognised independent cause of lymphoedema.
f) Immobility
Muscle movement helps lymph fluid flow. Being inactive for long periods — such as after surgery, stroke, or hospitalisation — can reduce this pumping effect and cause swelling to start or worsen.
Less Common Causes of Lymphoedema
While less frequent, some other medical problems may also cause lymphoedema. These include:
- Autoimmune conditions: Such as lupus or rheumatoid arthritis
- Deep vein thrombosis (DVT): A clot can block normal lymph return
- Heart failure: Fluid overload may indirectly stress the lymphatic system
Even though these are rare, they can combine with other risk factors to increase the chance of developing lymphoedema.
Understanding Risk Factors
Knowing what causes lymphoedema also means knowing who is at risk. You may be more likely to develop the condition if you:
- Have had cancer surgery or radiation that involved lymph nodes
- Experience repeated cellulitis or skin infections
- Have a family history of lymphatic disorders
- Have undergone vascular or lymphatic surgery
- Are obese or lead a sedentary lifestyle
Being aware of these risks helps with prevention and early action.
Summary
The causes of lymphoedema include both inherited and acquired problems in the lymphatic system. Whether due to faulty development, cancer treatment, infections, or injury, the result is the same — fluid that can’t drain properly. Understanding these causes is key to identifying the condition early and avoiding long-term complications.
