Lymphedema is an abnormal accumulation of a lymphatic fluid that might cause swelling, usually in limbs. It might occur when there is a malfunction in the lymph transport, either because there is an inherent inborn defect in the lymphatic system development (primary lymphedema), or because  lymph vessels and nodes  are damaged , removed or blocked (secondary lymphedema). Lymphatic fluid, rich in proteins, accumulates in spaces between the cells, causing an extremity to swell. It should not be mixed up with swelling due to venous insufficiency, because causes, mechanisms and outcomes are completely different.

What causes lymphedema:

Secondary lymphedema is the most common kind. It is usually caused by surgery, radiation treatment, spreading of tumor, infection or trauma. Radical surgical procedure that require removal of the lymphatic nodes (such as mastectomy -removal of the breast due to the breast cancer, gynecological surgery, surgery on  a prostate or bowel ) put patient at higher risk of developing lymphedema.