According to the American Osteopathic College of Dermatology, age spots, also known as liver spots, hyperpigmentation or lentigines, may appear on the chest, face, back of the hands or torso, and are considered a harmless skin condition. These darkened skin patches are mainly due to excess melanin, a condition also known as hyperpigmentation.
According to MayoClinic.com, age spots or solar lentigines, are flat, black, brown or gray spots that usually appear on areas of the skin most exposed to the sun. Age spots are common for adults over 40 years of age, but may also affect younger people. The sun emits invisible rays of ultraviolet light or UVB rays. The UVB radiation attacks the skins pigment cells which react by overproducing melanin. The melanin darkens the skin to act as a filter from the harmful rays. Freckles and brown spots are examples of skin damage that occur as a direct result of exposure to UVB rays. People with fair skin who spend a lot of time in the sun are more likely to develop age spots.
Dark spots that appear on the face, chest or other areas due to hormonal changes in the body look very similar to age spots but are usually larger in size. Often referred to as the "mask of pregnancy" when they occur on the face, melasma or chloasma spots occur as a result of fluctuating hormones in the body that stimulate an overproduction of melanin. In addition to pregnancy, woman taking birth control pills may also experience hormone related hyperpigmentation.
The AOCD states that other causes for dark pigmentation are related to skin diseases such as acne. Once the condition clears, dark spots may be left on the skin. In addition to acne, hyperpigmentation may occur after surgery or after an injury to the skin. When exposed to the sun, these spots or patches may become darker as the melanin works to absorb the UVB rays and protect the skin from further damage.
The American Skin Association recommends you protect your skin by following a few rules. Avoid the sun between the hours of 10 a.m. and 4 p.m. If you have to be in the sun, wear protective clothing. Use a sunscreen with an SPF of 15 or higher no matter what your skin type, and avoid indoor tanning.