The three steps to curing discoloration.
It doesn't matter where on your body the skin discoloration is - face, neck, arms, legs etc. the procedure for removing the hyperpigmentation is the same. Start with very gentle exfoliation and a skin lightening cream plus a sunblock.
If that doesn't help the next steps are to step up the exfoliation with microdermabrasion, skin peeling treatments or one of the more gentle lasers. Here is a video of some advice on how to treat skin discoloration problems from Dr Brandith Irwin
Whether you are using creams, exfoliants or lasers - always protect your skin from UV radiation during and after treatment with a broad spectrum sun block and then stay out of the sun anyway.Patience!
When you start, you have to be scrupulous about applying the lighteners and especially the sunblock! Half an hour in sunshine without a sunblock can undo months of treatment! The first thing you must do is buy a good, broad-spectrum sunscreen, the highest factor you can find, and use it! Even in winter, even if its cloudy, even if its snowing.
Sun exposure will reverse the results of your treatment for the same reason that freckles, age spots, and other darkened skin patches can become worse when your skin is exposed to the sun! This is because melanin is there to absorb the energy of the sun's dangerous ultraviolet radiation and protect your tissues from it. A sun tan is always the result of skin damage. Any sun exposure will damage your skin. You might want to take supplements or allow a small amount of sun to reach non-problematic areas of your body for 30 minutes a week though - just ordinary daylight, perhaps on your feet or ankles so you do not get a vitamin D deficiency.Next you need an retinoid type of skin treatment such as Retinol, Retin A or, my personal favorite - Rose hip seed oil - or perhaps a peel.
Then you apply hydroquinone cream or one of the other skin lighteners.
If you keep at that for six months and still have no joy, there are now some very effective laser treatments for skin discoloration. The q-switched ruby and other 'pigmented lesion lasers' usually remove pigment without scarring, but a test spot in an inconspicuous place is always advisable.