Introduction and natural history

Lymphedema occurs when there is an imbalance of the lymphatic load in relation to the transport capability of the lymphatics. Lymphedema presents as swelling of any tissue but typically it manifests with swelling of a limb. Lymph flow is impaired and cannot return back to the circulation, resulting in formation of edema, chronic inflammation, and fibrosis of the tissue.

A normal lymphatic system can manage an increased protein and water load without leading to edema. However, other factors that increase the capillary filtration or impair lymphatic drainage can alter the equilibrium causing clinical edema. The increase in capillary filtration is known as high-output lymph failure. It occurs when the lymph flow is increased and incapable of keeping up with the microcirculatory demand, such as portal hypertension secondary to cirrhosis. The impaired lymph flow caused by blockage of lymph flow is low-output lymph failure, that presents as lymph stasis.

Lymphedema is classified as primary or secondary. Primary causes are usually congenital or hereditary from abnormalities of the lymphatic vessels. Secondary lymphedema is typically the result of blockage from tumor compression, or dissection of the lymph nodes or infections (filariasis). In the US the most common cause of secondary lymphedema is cancer and cancer treatment, but filariasis is the most common cause of lymphedema worldwide.

Clinical manifestation

The most common symptoms of lymphedema are presented in Table 54.2. These are mostly subjective symptoms that should be closely monitored.