One of the main ways melanoma spreads is through the lymphatic system – part of your immune system. The lymph system carries disease-fighting white blood cells to and from your bloodstream, to all parts of your body. Cancer cells can enter the lymph system and get carried to lymph nodes far from the original cancer. Melanoma that has spread to one or more lymph nodes is stage III cancer. What Happens When Melanoma Spreads As soon as cancer cells get into a lymph vessel near your melanoma, it means your cancer has started to spread. Affected lymph nodes usually swell. Your doctor will check for swollen lymph nodes near your melanoma. Lymph nodes are usually painless, but they may be painful if they are pressing on a nerve. If cancer cells block lymph flow, fluid can leak out of lymph vessels and cause swelling. The medical term for this is lymphedema. The spread of cancer can cause lymphedema. So can some cancer treatments, like surgery and X-ray treatment. Lymphedema can affect any part of your body. It's most obvious when it develops in your legs or arms. Symptoms may include: Swelling Hair loss Tightness Heaviness Burning Itching Trouble moving Diagnosing Lymph Node Spread If you have swollen lymph nodes near your melanoma, your doctor may remove them during your first treatment. The doctor may also remove the lymph nodes closest to the swollen ones. Treatment after surgery is intended to kill any cancer cells still in your lymphatic system. If your doctor cannot feel any lymph nodes but your melanoma is thick or ulcerated (like an open sore), the doctor may do tests on the lymph nodes closest to your melanoma. The doctor removes the nodes and checks them under a microscope. This is called a sentinel node biopsy. Managing Lymphedema Let your doctor know right away if you notice a swollen lymph node or lymphedema. The doctor may need to change your treatment plan. Also, if you have lymphedema, be extra careful to avoid skin injury. Lymphedema increases your risk of infection. Be sure to keep your skin clean and moist. And don't get an injection or blood test in an arm or leg that has lymphedema. The needle puncture increases your risk of infection. Other tips to help you manage lymphedema: Don't cross your legs while sitting. Change sitting positions often. Keep your swollen leg or arm above the level of your heart when you're resting. Do not apply heat to areas of lymphedema. Ask your doctor about: Using a compression sleeve or stocking to reduce swelling Recommending some light exercise Trying massage therapy to reduce your swelling Key Takeaways Cancer cells in the lymph nodes means melanoma has spread. Lymphedema can occur if the lymphatic system becomes blocked by the cancer or because of a cancer treatment. You'll need to take extra precautions to avoid infection if you have lymphedema. You have several options to manage lymphedema.