To protect itself from the damaging effects of the sun, your skin increases its production of the dark brown pigment called melanin. The extra melanin makes your skin look darker or sun-tanned. In some cases, the sun causes an uneven increase in melanin production, which produces irregular coloring (pigmentation) of the skin. The sun can also cause a permanent stretching of small blood vessels, giving your skin a mottled, reddish appearance.
Damage to darker skin
Melanin is the dark brown pigment in the top layer of skin (epidermis) that gives skin its color. This pigment protects the deeper layers of skin from sun damage. The more melanin in the skin, the darker the skin appears and the more protection it has against sun damage.
People with medium or dark complexions naturally have more protection than do people with lighter complexions. But they still can experience sun damage. This man's face shows signs of sun damage — increased areas of irregular pigmentation and wrinkles.
Solar lentigines on the forehead
Solar lentigines (len-TIJ-ih-neze) are flat spots of increased pigmentation. They're usually brown, black or gray and vary in size. And they usually appear on areas most exposed to the sun, such as the face, hands, arms and upper back. These spots, also referred to as age spots or liver spots, are common in older adults. They also occur in younger people who spend a lot of time in the sun without protecting their skin.
Solar lentigines on the back
Solar lentigines tend to become more numerous with repeated sun exposure and with advancing age. Sometimes they develop in large numbers, as seen on this man's upper back. They're similar to freckles, though freckles tend to be smaller and develop earlier in life.
A dark brown lesion on the lips, called labial lentigo, can develop after repeated sun exposure. In most cases, labial lentigo is a single spot that forms on the lower lip.
Ultraviolet radiation breaks down the skin's connective tissue — collagen and elastin fibers — that lies in the deeper layer of skin (dermis). Without the supportive connective tissue, the skin loses its strength and flexibility. This condition, known as solar elastosis (e-las-TOE-sis), is characterized by vertical creases, deep wrinkles, and loose or sagging skin.
Also referred to as "mask of pregnancy," melasma (muh-LAZ-muh) is a brown darkening of facial skin. Melasma likely occurs from a combination of factors, including exposure to sunlight and an increase in the female hormones estrogen and progesterone.
Melasma often affects women who:
- Have dark skin
- Take oral contraceptives or hormone therapy
- Are pregnant
The dark patches usually occur on the cheeks and forehead. Melasma usually fades during winter months in northern latitudes but returns in spring. It also tends to fade after pregnancy or when you stop taking oral contraceptives or hormone therapy.
Irregular areas of reddish-brown pigmentation characterize poikiloderma (POI-kih-loe-DUR-muh). It's most common on the neck and chest in chronically sun-exposed areas.
Actinic keratoses (ak-TIN-ik ker-uh-TOE-seez) appear as rough, scaly raised patches that range in color from almost white to tan to dark pink or brown. Also called solar keratoses, these patches are commonly found on the face, ears, lower arms and hands, and lower legs of light-skinned people whose skin has been damaged by the sun. If left untreated, actinic keratoses may progress to a type of skin cancer known as squamous cell carcinoma.
Lentigo maligna is a type of growth that develops in areas of long-term sun exposure, such as your face, hands or legs. Lentigo maligna starts as a dark flat spot that slowly darkens and enlarges. Eventually the spot may develop into a melanoma, a type of skin cancer that begins in the top layer of skin and then invades the underlying skin layer. See your doctor if you notice a:
- New skin growth
- Bothersome change in your skin
- Change in the appearance or texture of a mole
- Sore that doesn't heal or a bruise that fades and returns