Most brown spots on the back of the hands are from chronic sun exposure. For the benign ones there are many types of treatment, including topical treatments that you can apply yourself and other treatments performed by a dermatologist. There are a number of vitamin A type creams that can be prescribed and there is a relatively new product called 'SolageT' which is vitamin A combined with a bleaching product. It is a prescription that you paint on yourself. Liquid nitrogen or a number of laser treatments can also be used to remove these spots. Best of luck, Richard Thomas