Definition: Lymphoedema is a condition of localised fluid retention caused by a compromised lymphatic system. There is an accumulation of excessive lymph fluid and consequently a swelling of subcutaneous tissues due to obstruction, destruction and/or hypoplasia of lymph vessels. When lymphatic impairment becomes so great that the lymph fluid exceeds the lymphatic system's ability to transport it, an abnormal amount of protein-rich fluid collects in the tissues of the affected area. Left untreated, this stagnant, protein-rich fluid causes tissue channels to increase in size and number, reducing the availability of oxygen. This interferes with wound healing and provides a rich medium for bacterial growth that can result in lymphangitis.

Lymphoedema develops in a number of stages, from mild to severe:

Grade 1 (mild oedema): involves the distal parts such as a forearm and hand or a lower leg and foot. The difference in circumference between affected limb and unaffected limb is less than 4 centimetres, and other tissue changes are not yet present. The lymphatic vessels have sustained some damage which is not yet apparent, and lymph is still efficiently moved.

• Grade 2 (moderate oedema): involves an entire limb or corresponding quadrant of the trunk. The difference in circumference between affected limb and unaffected limb is more than 4 but less than 6 centimetres. Tissue changes, such as pitting, are apparent – i.e., when pressed by the fingertips, the affected area indents and holds the indentation. Upon waking in the morning, the limb or affected area is normal or almost normal in size.

• Grade 3 (severe oedema): present in one or more limbs and its associated trunk quadrant. The difference in circumference is greater than 6 centimetres. Significant skin alterations, such as cornification or keratosis, cysts and/or fistulae, are present. Additionally the patient may experience repeated attacks of erysipelas. The tissue now has a spongy consistency and is non-pitting – i.e., when pressed by the fingertips, the tissue bounces back without any indentation.

• Grade 4 (gigantic oedema): also known as elephantiasis. In this stage of lymphoedema, the affected extremities are huge due to almost complete blockage of the lymph channels. At this stage, the swelling is irreversible and usually the affected area is very large. The tissue is hard (fibrotic) and unresponsive.

Aetiology/Major causative factors and risk factors that can contribute to the incidence of lymphoedema include the following:
• Genetics–inherited (primary) lymphoedema.
• Injury to the lymphatic vessels (secondary)–e.g.,after lymph node dissection, surgery and/or radiation therapy.
• Damage to the lymphatic system is often caused by the treatment of cancer, most notably breast cancer.
• Parasitic infections (e.g., toxoplasmosis, tropical filariasis).
• Vascular abnormalities.
• Aircraft flight (likely due to decreased cabin pressure).
• Some medications (e.g.,Tamoxifen)

Common signs and symptoms of lymphoedema include:
• Heavy swollen limbS or localised fluid accumulation in other body areas
• Swollen lymph nodes
• Dyslipidaemia
• Headaches
• Frequent infections, colds and flus–i.e. , weakened immune system
• Allergies
• Chronic fatigue
• Skin ulceration and cellulitis
• Discoloration of the skin overlying the lymphoedema