The lymphatic system has developed from the venous system and covers the whole body like a net. It consists of lymphatic vessels, which constitute a drainage and a transport system, as well as numerous lymph nodes. The lymphatic system collects, filters, and returns lymphatic fluid to the venous system.
Lymphatic diseases are characterized by impaired lymph flow to the circulatory system. As a result of lymph vessels failure, swelling of the soft tissue develops (lymphedema), which is most often caused by surgical procedures within the lymphatic system (secondary lymphedema) and much less often of congenital nature (primary lymphatic).