Varicose ulcers affecting an elderly person's lower leg. Ulceration of the skin occurs as a complication of varicose veins (veins that become distended and twisted, just beneath the skin, due to restriction in blood supply). The superficial (saphenous) veins of the leg are most commonly affected. In severe cases, as here, tissues of the leg become starved of oxygen and nourishment. This causes the skin to become thin, hard, dry, scaly, and discoloured, leading to ulcer formation.