Lymphatic system is a network of microscopic vessels assisting veins in delivering the blood back to the heart.

Conditions affecting lymphatic circulation are not very common in modern Western society. The most often one is a lymphedema, a disease caused by compromised lymphatic return from an extremity. The above leads to the progressive swelling of the involved extremity, which is very different of edema due to other conditions, such as heart failure, kidney failure etc.