With varicose veins, heavy legs, or thrombosis, the accumulation of water remain in the tissue over a long period of time. In the long run they will lead to skin lesions. At first, hardens the skin (skin sclerosis), also causes disorders of the skin color (pigmentation).

These changes occur almost exclusively in the area of the medial malleolus and the inner lower leg. Serious consequence is the death of skin tissue. This creates the so-called “open leg” or leg ulcer (ulcus cruris).

http://www.ellviva.de/Gesundheit/Venenerkrankungen-Symptome.html