A venous lake is a small blood vessel (vein) in the skin, which over time has become enlarged. It has the appearance of a small soft blue lump of up to 1cm diameter which may be flat or slightly dome-shaped. It usually affects sun-exposed areas of the skin, most commonly the rim of the ear or the lower lip.
It is thought that long-term sun exposure of the skin causes venous lakes and they are usually seen in people older than 50. They are not contagious or cancerous.
Usually, venous lakes do not cause any symptoms. However, after they have been knocked or caught, they may become painful or bleed.