What Is It?
Lymphedema is the buildup of fluid called lymph in the tissues under your skin when something blocks its normal flow. This causes swelling, most commonly in an arm or leg.
Lymph normally does an important job for your body. It carries foreign material and bacteria away from your skin and body tissues, and it circulates infection-fighting cells that are part of your immune system.
Lymph flows slowly through the network of vessels called your lymphatic system. Lymph flow stops at points along the way to be filtered through lymph nodes. Lymph nodes are small bean-shaped organs that are part of your immune system.