Understanding Lymphoedema: Causes & Types

Written & reviewed by the BestDoctors.sg editorial team · Last updated 28 Aug 2026 · General information, not medical advice

How the lymphatic system fails

The lymphatic system relies on a network of vessels and nodes to move fluid out of the tissues. Lymphoedema develops when this drainage cannot keep up with the fluid being produced, either because the system was built with fewer or faulty vessels, or because part of it has been removed or blocked. The NHS explains that the result is the same in both cases: protein-rich fluid collects and the area swells. Over months and years, untreated swelling can make the tissue firmer and the skin thicker, which is why early management matters.

Primary lymphoedema

Primary lymphoedema is uncommon and is linked to genes that affect how the lymphatic system forms. It can be present from birth or appear later, most classically around puberty or in early adulthood. Doctors sometimes use older names such as Milroy disease, Meige disease or lymphoedema praecox to describe when it first appears. Because it reflects how the lymphatic system was built, it tends to be lifelong, but it responds to the same management as other forms. A family history of unexplained limb swelling can be a clue.

Secondary lymphoedema: cancer treatment

The most familiar cause of secondary lymphoedema in a cancer setting is treatment that affects the lymph nodes. Surgery to remove nodes, and radiotherapy to areas containing nodes, can disrupt drainage in the nearby limb or region. Breast cancer treatment can lead to swelling in the arm, hand, breast or chest; pelvic, gynaecological or prostate cancer treatment can affect a leg or the genital area; and head and neck cancer treatment can cause facial or neck swelling. Importantly, most people who have nodes removed do not go on to develop lymphoedema, and the risk can be lowered with good aftercare.

Secondary lymphoedema: other causes

Cancer is far from the only cause. Severe or repeated skin infections such as cellulitis can damage lymphatic vessels. Long-standing vein problems, sometimes called chronic oedema, can overload the lymphatic system. Reduced movement, such as after a stroke or with limited mobility, allows fluid to pool. Serious injury, burns or surgery to a limb can also play a part, and carrying a lot of excess weight can strain lymphatic drainage. Worldwide, a parasitic infection called filariasis is a major cause, although this is uncommon in Singapore.

Which parts of the body are affected

Lymphoedema most commonly affects one arm or one leg, but it is not limited to limbs. It can involve both legs, the breast or trunk, the head and neck, or the genital area, depending on where the lymphatic drainage is disrupted. The pattern often reflects the cause; for example, breast cancer treatment tends to affect the arm on the same side. Swelling may be mild and come and go early on, becoming more constant if it is not managed.

How lymphoedema is diagnosed

Lymphoedema is usually diagnosed clinically, meaning a doctor or lymphoedema therapist recognises it from your history and by examining the swelling, rather than needing a single definitive test. They will ask about cancer treatment, infections, injuries and family history, and may measure the limb and compare sides. Occasionally, specialised imaging such as lymphoscintigraphy is used to look at how lymph is draining, or scans are done to rule out other causes of swelling such as a blood clot. Cancer Research UK notes that ruling out other causes is an important part of assessment.

Stages of lymphoedema

Clinicians sometimes describe lymphoedema in stages to guide treatment. In simple terms, a latent stage means the drainage is impaired but there is no visible swelling yet; an early stage means swelling that may reduce with elevation and leaves a dent when pressed; and later stages mean more constant swelling with firmer tissue and skin changes. The National Cancer Institute describes a staging system along these lines. Stages are a guide, not a fixed path, and good management can keep many people stable for years.

Why identifying the cause helps

Pinning down the type and cause is not just labelling. It shapes practical decisions: someone at risk after cancer treatment focuses on early detection and protecting the at-risk limb, while someone with vein-related swelling may need their circulation addressed too. It also helps you recognise your own risk factors, such as avoiding injury or infection in a vulnerable limb. If you are unsure why you have swelling, ask your doctor to explain the likely cause, as this anchors the rest of your care.

Related lymphoedema topics

• Living with lymphoedema
• Compression garments & bandaging
• Skin care & preventing infection
• Manual lymphatic drainage & massage
• Exercise & movement
• Lymphoedema after cancer treatment
• Managing swelling & daily life
• Lipoedema & lymphoedema: the difference
• Emotional wellbeing & support
• Physiotherapists in Singapore

Sources

• NHS – Lymphoedema causes: nhs.uk
• Cancer Research UK – Lowering your risk of lymphoedema: cancerresearchuk.org
• Cancer Research UK – Diagnosing lymphoedema: cancerresearchuk.org
• National Cancer Institute – Lymphedema (PDQ) patient version: cancer.gov
• Better Health Channel – Lymphoedema: betterhealth.vic.gov.au
• Lymphoedema Support Network – What is lymphoedema: lymphoedema.org