The more common name for Lentigos is Liver Spots.  They are flat, brown spots that are common among in 75% of Caucasains aged 60 and older.  They are really not associated with your liver at all but are a result of sun exposure also called sun spots and will usually increase in size and number as one ages. 

Lentigos are not usually malignant unless their color is uneven or the edges are not clearly defined.  If you have any of these, you need to see a dermatologist to have them checked. 

The best treatment is prevention.  Avoid sun exposure between 10 AM-2 PM, use sunblock, and wear a hat when you will be in the sun.  If it is too late for prevention, there are lightening products that can be used.  These products contain hydroquinone or natural lightening ingredients such as licorice root or bearberry.   An aesthetician can perform a series of chemical peels or microdermabrasion treatments.  If these treatments are not effective enough, a physician can use liquid nitrogen, IPL treatments, or a series of TCA peels.  Sunscreen is imperative during any treatment protocol chosen.