What causes lymphedema?
Primary lymphedema causes
Primary lymphedema is an abnormality of an individual's lymphatic system and is generally present at birth, although symptoms may not become apparent until later in life. Depending upon the age at which symptoms develop, three forms of primary lymphedema have been described. Most primary lymphedema occurs without any known family history of the condition.
- Congenital lymphedema is evident at birth, is more common in females, and accounts for about 10-25% of all cases of primary lymphedema. A subgroup of people with congenital lymphedema has a genetic inheritance (in medical genetics termed "familial sex-linked pattern"), which is termed Milroy disease.
- Lymphedema praecox is the most common form of primary lymphedema. It is defined as lymphedema that becomes apparent after birth and before age 35 years and symptoms most often develop during puberty. Lymphedema praecox is four times more common in females than in males.
- Primary lymphedema that becomes evident after 35 years of age is known as Meige disease or lymphedema tarda. It is less common than congenital lymphedema and lymphedema praecox.
Secondary lymphedema causes
Secondary lymphedema develops when a normally-functioning lymphatic system is blocked or damaged. In the U.S., breast cancer surgery, particularly when combined with radiation treatment, is the most common cause. This results in one-sided (unilateral) lymphedema of the arm. Any type of surgical procedure that requires removal of regional lymph nodes or lymph vessels can potentially cause lymphedema. Surgical procedures that have been associated with lymphedema include vein stripping, lipectomy, burn scar excision, and peripheral vascular surgery.
Damage to lymph nodes and lymph vessels, leading to lymphedema, can also occur due to trauma, burns, radiation, infections, or compression or invasion of lymph nodes by tumors.
Worldwide, however, filariasis is the most common cause of lymphedema. Filariasis is the direct infestation of lymph nodes by the parasite Wuchereria bancrofti. The disease is spread among persons by mosquitoes, and affects millions of people in the tropics and subtropics of Asia, Africa, Western Pacific, and parts of Central and South America. Infestation by the parasite damages the lymph system, leading to swelling in the arms, breasts, legs, and, for men, the genital area. The entire leg, arm, or genital area may swell to several times its normal size. Also, the swelling and the decreased function of the lymph system make it difficult for the body to fight infections. Lymphatic filariasis is a leading cause of permanent disability in the world.