What Causes Brown Patches On The Scrotum And Foreskin That Is Becoming More Dark Apart From Pigmentation On The Chest?

Since went through puberty 15 years ago my scrotum and foreskin have been getting more and more brown patches on them..now the left side of my scrotum has turned darkish brown right side still white with little brown patches and foreskin brown patches everywhere..i do suffer from pigmentation on my chest but that is a lighter colour of brown should I be worried?..