Hi Due to increased pressure in bigger blood vessels and weakness of tiny blood vessels of leg (genetically or due to prolonged standing or walking) red blood cells come out and get exposures in skin which change colour over time and are seen as dark spots from surface. As pigment lies deep in skin, only skin creams won't help. It's not a disease itself and won't harm you in anyway but consult a qualified dermatologist to know underlying reasons in your case and take treatment which may help arrest further spread. Hope this helps. Regards Dr Vijay Adhe Eternis Skin & Hair Care Pune www.eternisclinic.com