There are several methods of lightening dark skin spots. However, anyone with hyper pigmented spots on

 the skin should first have them checked by their dermatologist to rule out either precancer or skin cancer.

 This can sometimes be done by a simple visual examination. Or, it may require a skin biopsy. If  the 

 darkened skin areas are deemed to be benign, one or more of the following methods may be used

 to lighten them.

 A topical (i.e., applied from the outside to the skin) medication called hydroquinone, sometimes

 combined with a vitamin A derivative called tretinoin is one of the most effective, noninvasive

 methods of lightning dark skin spots.

  Other methods include the application of intense pulsed light and various types of lasers,

 chemical peels (especially those containing trichloroacetic acid   or glycolic acid). These

 peels can also help eliminate fine lines and wrinkling caused by sun exposure and/or aging of the skin.

 In addition, products containing azelaic acid, which is component of grains such as barley, rye

 and wheat, and vitamin C (ascorbic acid) can also have a skin lightening effect.

 One can also consider the use of an old remedy, lemon juice which contains citric acid and 

 has been used as a skin  lightener for a long time.

 However, one must be very careful with the application time when applying lemon juice

 to the skin  since it can dry out the skin and is a potent photosensitizer that can cause sunburn

 when exposed to the sun.