The cause is often unknown, but abnormalities of the lymph system seem to be responsible for some cases. Acquired lymphedema occurs after surgery, radiation therapy, infection, or injury. Surgical operations that require removal of lymph nodes greatly increase the risk for lymphedema. Swelling can occur immediately or weeks, months, or even many years after such surgery. Radiation therapy can cause scarring of lymph nodes and vessels, which interrupts the normal flow of lymph.
Radiation therapy can also cause burns similar to sunburn.
After radiation therapy, skin should be examined carefully for changes in temperature, color, or blistering that could lead to infection and lymphedema. What to watch for Signs of lymphedema include a heavy sensation in an arm or leg, skin tightness, and decreased flexibility in the hand, wrist, or ankle. You may feel that your clothing is suddenly too tight or that a watch or ring is uncomfortable. If you notice swelling or any of these changes, call your doctor right away. When lymphedema is not treated, fluid rich in protein accumulates and causes swelling and hardening of the tissues.