T.B.
First always see a dermatologist when anything new appears or any changes. You never know when that spot could be something really serious.
With that being said, I have had these "sun spots" for about 10yrs. The doc told me they are referred to as a "pregnancy mask" I don't remember what the technical term was (FYI--I was not pregnant when this appeared, it was from the birth control pills). I was also told once I stopped taking birth control pills or I wasn't pregnant it would fade away--yeah right! I tried Lustra bleaching cream a while back, I really didn't notice a difference. But to keep it from getting worse, I use a high spf sunscreen everyday and reapply if I'm going to be out in the sun.