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 or pigmentation of the skin. The sun can also cause a permanent stretching (dilation) 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 normal 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.
Though people with medium or dark complexions naturally have more protection than do people with lighter complexions, they still can experience sun damage. This man has dark skin, but his face still shows signs of sun damage — increased areas of irregular pigmentation and wrinkles.
Solar lentigines on the forehead
Also referred to as liver spots or age spots, solar lentigines (len-TIJ-ih-neez) are flat spots of increased pigmentation — usually brown, black or gray. They vary in size and usually appear on the face, hands, arms and upper back — areas most exposed to the sun. Though common in older adults, solar lentigines also can occur in younger people who spend too much time in the sun.
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 different from freckles in that freckles are red or light brown, are smaller in size, tend to develop earlier in life, and usually lighten in winter months.
A dark brown lesion, called labial lentigo, can develop on the lips after repeated sun exposure. In most cases, labial lentigo is a single spot that forms on the lower lip, which is often more exposed to sunlight.
Ultraviolet radiation breaks down the skin's connective tissue — collagen and elastin fibers — which lie 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 with dark skin and those who take oral contraceptives or hormone therapy, or who are pregnant. The dark patches usually occur on the cheeks, forehead, nose and chin. Melasma typically worsens after sun exposure.
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 or solar keratoses (ker-uh-TOE-sees) appear as rough, scaly raised patches that range in color from flesh colored to dark pink or brown. They're commonly found on the face, ears, lower arms and hands of fair-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, a bothersome change in your skin, a change in the appearance or texture of a mole, or a sore that doesn't heal.