Sun spots, also known as age spots or liver spots (singular: lentigo, plural: lentigines), are harmless, flat, brown discolorations of the skin which usually occur on sun-exposed surfaces of the face, back of the hands, and trunk. These brown spots are caused by years of over-exposure to the sun; some find them cosmetically bothersome. As much as 90 percent of the visible changes commonly attributed to aging are caused by the sun.
Freckles are simply small lentigines which generally appear on children who are sensitive to the sun and are exposed to sufficient sunlight; they will darken with sun exposure. People with lighter skin and blue eyes and blond or red hair are especially susceptible. Usually people with freckles are more sensitive to the sun, so sun protection is even more important.
Hormones may play a role in skin pigmentation: changes may be due to birth control pills, pregnancy or various stages of menopause. These changes are not the same as age spots, but treatment is similar.
Sun spots are harmless but must be distinguished from more significant brown spots which are abnormal in size or color and may need to be biopsied by the dermatologist. It can be difficult at times to determine if a dark spot is from the sun and harmless or requires medical attention. If, among all your spots you find one that’s an “ugly duckling” – it stands out from the rest because it’s a different color, size, texture or border, you should get it checked by your dermatologist; it may be a skin cancer.
The only preventive measure against sun spots is liberal use of sunscreen, avoidance of sun exposure, and faithful use of protective clothing. The sunscreen should be SPF 30 or higher and should be applied to the face, hands, and other sun exposed skin areas thirty minutes prior to sun exposure. After developing these brown spots, you may want them removed for cosmetic reasons: there are a myriad of topical agents to remove these brown spots. The topical therapies may contain hydroquinones (bleaching agents). Other methods to remove these sun spots are chemical peels, liquid nitrogen treatment, or special lasers.