The lymphatic system runs throughout the body. Unlike the system of vessels that transports the blood, the lymphatic system lacks independent musculature to pump the lymph through the body. Instead, the lymphatic flow occurs secondarily to the pumping action in nearby blood vessels (primarily the veins) and as a simple result of physical movements of the body. Lymph gains its contents from the blood, and the lymph vessels (which are larger than capillaries but much smaller than the smallest veins) drain the majority of their contents back into the blood stream via the thoracic duct at the base of the neck.

There are small, bean-shaped lymph nodes laced along the lymphatic vessels, but the major clusters are in the neck, armpits, abdomen, and groin. During an infection, it is common for the lymph nodes to become enlarged, sometimes noticeably so, as they fill with immune cells and the debris from immune attack.

Lymphedema (also spelled lymphoedema), is a swelling of the subcutaneous tissues by accumulation of lymph fluid. The disorder has become a common medical concern as the result of modern treatments for breast cancer: mainly surgery, but also radiation therapy. In many cases of breast cancer, it is standard practice to remove tissues beyond the main tumor mass. In addition to taking some surrounding breast tissue (or all, in the case of mastectomy), several or all of the adjacent lymph nodes in the arm pit are excised. The node removal (or damage, in the case of radiation therapy) reduces the efficacy of lymph movement, and  lymphedema can result.

Lymphedema can also occur as the result of injuries as well as from any disease process that damages or obstructs the lymph nodes. In addition, lymphedema of the legs occurs in elderly persons suffering from chronic venous insufficiency, since the pumping of blood through the veins contributes to the movement of lymph.

The main symptom of lymphedema is the evident swelling, with only slight pitting, which can increase the volume of the affected limb by up to 50% for the arms and up to about 25% for the legs. Other symptoms, especially in the more severe cases, may include pain, tightness, tension, heaviness of the limb, hardness of the tissues, stiffness of the affected limb, and, in persistent cases, there can be ulceration due to the impaired circulation.

Lymphedema is usually treated by a combination of non-invasive physical methods. These include manual lymph drainage (in essence, massaging the fluid out of the arms), compressive bandaging (preventing accumulation of fluid by restricting arm volume), and physical exercises (that promote lymph drainage). These methods not only can greatly reduce lymphedema, but, in many cases, the results are lasting (at least, until local trauma or other inducing event triggers another bout of swelling).

Chinese Medicine has a long history of treating conditions that are similar to, or would be classified as lymphedema today. in ancient times, areas the body, which today we know contain lymph nodes, were recognised easily become lumpy, though fluid & nodes same sense it is now modern western medicine, was unknown.

The condition of lymphedema fits the Traditional Chinese Medicine illness category of "Phlegm-Damp accumulation". The fluid swelling would, by itself, lead one to classify the disease as a dampness accumulation (which corresponds directly to the Western term edema). The phlegm aspect of the condition is related to the thickness of the fluids involved. As we know from modern research, lymph is a somewhat milky fluid that replenishes the blood with chyle (emulsified fat), erythrocytes (red blood cells), and leukocytes (white blood cells), and which also carries protein debris. A more watery accumulation based on a less-dense fluid, as occurs in cases of pitting edema, would be considered a moisture accumulation but not a phlegm-damp accumulation in Chinese Medicine terminology.

Both Acupuncture and Chinese Herbal Medicine see to address the issue of phlegm-damp accumulation and to any that correspond most closely to lymphedema. Chinese Medicine can also be beneficial to other more common problems of lymph node swelling (lymphadenitis), numbness and aching in the arms (corresponding to dampness accumulation), and at swellings, lumps, and pains in the breasts.

Both Taiji Quan (Tai Chi) and Qi Gong exercises can also be beneficial self care in the treatment and management of lymphedema.