The most extreme consequence of varicose vein disease is venous ulcers. They are also called stasis ulcers. These are open wounds on the lower portion of the legs, usually around the ankle, though the first symptoms can be swelling, dark red or purple discoloration and thickness of the skin. They will not heal on their own.
Often they are caused by venous insufficiency. Your veins have one-way valves that keep blood flowing toward the heart. In venous insufficiency, the valves are damaged, and blood backs up and pools in the vein. Fluid may leak out of the vein and into the surrounding tissue. The resulting pressure interferes with the circulation of blood to the skin causing a breakdown of the tissue and an ulcer.
Compression bandages and wound care can help with this problem. But, if the ulcers arise from venous insufficiency they will not go away without treating the underlying vein disease. For this reason, if you have a leg ulcer you need to see a vein doctor or phlebologist.