Lymphedema is a condition in which excess fluid collects in tissue and causes swelling. It may occur in the arm or leg after lymph vessels or lymph nodes in the underarm or groin are removed or treated with radiation.
The best way to understand what lymphedema is, is to break the word itself into parts: "lymph" + "edema". First of all, "edema" is a common term that we associate with the word "swelling". "Lymph" however, is a little more confusing for most people. Most of us are aware that we have "lymph nodes" (feel them under your jaw, your armpits, etc.) and we may even be aware that these nodes are part of the lymphatic system which have multiple functions (filtration, production of immune cells, and fat transportation) but many people confuse 'lymph' with 'water' and herein lies all the confusion in both understanding the basic anatomy and the underlying pathology of the disease process in lymphedema. Lymph is not water! It is a highly proteinous fluid that, when combined with an inability to flow freely through your circulatory system, results in lymphedema: an edema of a highly proteinous nature. This is important to understand because bacteria thrive in a protein environment (such as 'agar' used in a laboratory)- when an arm (or leg) becomes edematous and swells, a simple bug bite or innocuous cut to the skin can be a life-threatening event.. Why? Because your skin, the largest organ of you body, is now compromised, and the dermal lymphatics (under the skin) are now a perfect medium (like the agar) for the bacteria to thrive and grow on, which explains how the simple bite/sting/cut/hangnail can not only become infected but cause a far more serious condition called "cellulitis".