Your lymphatic system is crucial to keeping your body healthy. It circulates protein-rich lymph fluid throughout your body, collecting bacteria, viruses and waste products. Your lymphatic system carries this fluid and harmful substances through your lymph vessels, which lead to lymph nodes. The wastes are then filtered out by lymphocytes — infection-fighting cells that live in your lymph nodes — and ultimately flushed from your body.

Lymphedema occurs when your lymph vessels are unable to adequately drain lymph fluid, usually from an arm or leg. Lymphedema can be either primary or secondary. This means it can occur on its own (primary lymphedema) or it can be caused by another disease or condition (secondary lymphedema). Secondary lymphedema is far more common than primary lymphedema.

Causes of secondary lymphedema

Any condition or procedure that damages your lymph nodes or lymph vessels can cause lymphedema. Causes include:

  • Surgery. Lymphedema can develop if your lymph nodes and lymph vessels are removed or cut. For instance, surgery for breast cancer may include the removal of one or more lymph nodes in your armpit to look for evidence that cancer has spread. If your remaining lymph nodes and lymph vessels can't compensate for those that have been removed, lymphedema may result in your arm.
  • Radiation treatment for cancer. Radiation can cause scarring and inflammation of your lymph nodes or lymph vessels, restricting flow of lymph fluid.
  • Cancer. If cancer cells block lymphatic vessels, lymphedema may result. For instance, a tumor growing near a lymph node or lymph vessel could become large enough to block the flow of the lymph fluid.
  • Infection. An infection of the lymph nodes can restrict the flow of lymph fluid and cause lymphedema. Parasites also can block lymph vessels. Infection-related lymphedema is most common in tropical and subtropical regions of the globe and is more likely to occur in developing countries.

Causes of primary lymphedema

Primary lymphedema is a rare, inherited condition caused by problems with the development of lymph vessels in your body. Primary lymphedema occurs most frequently in women. Specific causes of primary lymphedema include:

  • Milroy's disease (congenital lymphedema). This is an inherited disorder that begins in infancy and causes your lymph nodes to form abnormally, leading to lymphedema.
  • Meige's disease (lymphedema praecox). This hereditary disorder often causes lymphedema in childhood or around puberty, though it can occur in your 20s or early 30s. It causes your lymph vessels to form without the valves that keep lymph fluid from flowing backward, making it difficult for your body to properly drain the lymph fluid from your limbs.
  • Late-onset lymphedema (lymphedema tarda). This occurs rarely and usually begins after age 35.
Nov. 15, 2011