Primary lymphoedema occurs when the lymphatic vessels or lymph nodes have not completely developed or have developed abnormally before birth. Primary lymphoedema may present at any time and is not always present from birth.
Secondary lymphoedema occurs as a result of damage to or obstruction of the normal lymphatic system, resulting in an inability of the lymphatic system to transport lymph back into the circulatory system. This may be caused by an infection of the lymph, trauma or surgery, venous insufficiency (varicose veins), a blood clot (post-thrombotic syndrome), cancer, obesity, untreated wounds or infections amongst others.
Surgical causes usually result from damage to the lymphatic channels as a side-effect of surgery or radiotherapy for cancer. This is typically seen as a complication following breast cancer surgery, melanoma and pelvic (gynaecological or prostate) surgery where the surgical lymph node removal or radiation in the armpit or groin have damaged the lymph vessels.
Destructive infection of the lymphatics typically results from infection from the roundworm Wucheria Bancrofti. It may also be from Brugia Malayi, and Brugia Timori worms. If the infection becomes chronic, lymphoedema results, known as elephantiasis