I have those, but I'm 50 and have not had the greatest diet in my 50 years. They say they are caused my a malfunctioning liver (such the word "liver spots") but I believe they could also be caused by fungus or bacteria, either internal or external, as well as parasites.
So, I started by cleansing, liver (flushes) and bowels ( Oxypowder ). Recently I decided to do a series of detox baths to help the process along. parasites absolutely hate oxygen, so I take the Oxypowder internally, and the other oxygen (H202 - hydrogen peroxide) externally.
One night a week I take a bath of 1 cup of 35% food grade H202 (hydrogen peroxide) along with 1/2 cups of Sea Salt , Epsom Salts and baking soda.
One night a week I take a bath of 1 cup of 35% food grade H202, along with one quart of Colloidal Silver (superior for fungus) that I make myself.
I figure that those spots will be history, and perhaps I won't look like I have 50 year old legs anymore.