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.
Lymph is formed from the fluid that surrounds cells in the body. It makes its way into very small lymphatic vessels. After traveling through these small vessels, lymph drains into deeper, wider lymph channels that run through the body. Eventually, lymph fluid returns to the blood.
Lymphedema occurs when there is inadequate lymph drainage from the body, usually from a blockage in a lymph channel. Lymphatic fluid builds up underneath the skin and causes swelling. Most commonly lymphedema affects the arms or legs.
Swelling from lymphedema can look similar to the more common edema caused by leakage from tiny blood vessels under the skin.
In most cases of lymphedema, the lymphatic system has been injured so that the flow of lymph is blocked either temporarily or permanently. This is called secondary lymphedema. Common causes include:
When lymphedema occurs without any known injury or infection, it is called primary lymphedema. Doctors diagnose three types of primary lymphedema according to when symptoms first appear:
All three types of primary lymphedema are probably related to the abnormal development of lymph channels before birth. The difference is when in life they first cause swelling of the legs or arms.
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