Sun damage accrues in response to cumulative UV exposure and becomes increasingly evident with time. It has been estimated that up to 90% of “age-related” skin changes are caused by the sun. Aside from the undesired cosmetic results, some of these changes are precancerous, and long-term sun damage may ultimately present as changes consistent with skin cancers. We will not be discussing skin cancers in this article, but you can read more about them here.
Did you know that the sun can cause…
…freckles? These flat, brown spots are indeed caused by sun exposure. They are more prevalent in light-skinned individuals and usually appear at a very young age. The brown spots are a result of increased melanin, which is the brown pigment released by melanocytes (the pigment-producing cells within our skin). An interesting point about freckles is that they fade in the winter. If a freckle does not fade in the winter, it may be another flat, brown spot called a lentigo simplex.
…uneven skin color? The melanocytes in your skin increase their production of melanin when they are exposed to the sun in order to protect your skin. This process does not occur evenly and can lead to scattered areas of hyperpigmentation, or darker coloring.
…thick skin with coarse wrinkles? This can be quite pronounced, and when it occurs on the back of the neck it is called cutis rhomboidalis nuchae.
…melasma? Melasma looks like a “mask” of flat, darker coloring that occurs in patches upon the face. It is symmetrical and usually occurs over the cheeks, forehead, and upper lip. It is common in females and, apart from UV radiation, is often associated with pregnancy and the use of birth control pills. It is caused by an increase in the number of melanocytes as well as an increase in their activity level.
© 2001-2009, Dermatlas
…idiopathic guttate hypomelanosis? These flat, white spots, usually located on the arms and the legs, are a mystery to many patients! Although their cause is unknown, they are linked to sun exposure, and biopsies of the skin shows a decrease in the number of melanocytes as well as the amount of melanin.
© 2001-2009, Dermatlas
…”liver spots” or “old-age spots”? These flat, tan or brown spots are actually called solar lentigines. They can spring up right after a sunburn or after years of tanning. They are characterized by an increase in the number of melanocytes, and are most commonly found on the neck, head, shoulders, and backs of the hands.
…solar elastosis? When the sun damages the supportive collagen and elastin fibers within the skin, the result is loose, sagging skin. This is referred to as solar elastosis. It is also characterized by deep wrinkles and vertical creasing.
…poikiloderma? Poikiloderma is characterized by red-brown pigment on the sides of the neck and the cheeks. It may be partly due to chemicals in perfumes and other cosmetic products that cause the skin to become more sensitive to the sun.
…changes in your blood vessels? Chronic sun exposure can cause your blood vessels to become more fragile, leading to solar purpura (minimal blood leakage beneath the skin) and easy bruising. It can also cause telengiectasias, which are dilated, superficial blood vessels.
…solar or actinic keratoses? These rough, scaly, and raised patches feel like gritty, coarse sandpaper and range from skin-colored to pink to brown. They are sometimes very subtle, and better appreciated with touch than sight, and other times very obvious with a very pronounced scale. They are most common on the face, a bald scalp, ears, forearms, and hands. These lesions should be assessed by a dermatologist for the following lesion: (1) They are a sign of excessive sun exposure, which is a risk factor for skin cancer (2) They are sometimes difficult to distinguish from a squamous cell carcinoma and may require a biopsy and (3) Less than 1 in 1000 cases have been evidenced to progress to squamous cell carcinoma and need to be treated or followed.
© 2001-2009, Dermatlas
…actinic cheilitis? This is the same as actinic keratosis, but it occurs on the lip.
© 2001-2009, Dermatlas
These changes can occur in both the young and the elderly, although they are most commonly seen in older persons. Some of these changes are irreversible and progressive, so it important to initiate sun protective practices early in life. If you still doubt that the sun is capable of inducing permanent skin changes, compare a sun-exposed area on your body to a non-sun-exposed area. The older you are and the more sun exposure you have obtained, the more impressive the difference will be!
REFERENCES:
Marks JG, Miller JJ. Pigmented Growths. In: Lookingbill & Marks’ Principles of Dermatology. 4th ed. Elsevier Inc; 2006:71-75.
Marks R,Rennie G,Selwood TS. Malignant transformation of solar keratoses to squamous cell carcinoma. Lancet. 1988; 1: 795-797.
Taylor CR, Stern RS, Leyden JJ, Gilchrest BA. Photoaging/photodamage and Photoprotection. J Am Acad Dermatol. 1990 Jan;22(1):1-15.
Wolff K, Johnson RA, “Section 10. Photosensitivity, Photo-Induced Disorders, and Disorders by Ionizing Radiation” (Chapter). Wolff K, Johnson RA: Fitzpatrick’s Color Atlas & Synopsis of Clinical Dermatology, 6e: http://www.accessmedicine.com/content.aspx?aID=5185968.
Young Antony R, Walker Susan L, “Chapter 89. Acute and Chronic Effects of Ultraviolet Radiation on the Skin” (Chapter). Wolff K, Goldsmith LA, Katz SI, Gilchrest B, Paller AS, Leffell DJ: Fitzpatrick’s Dermatology in General Medicine, 7e: http://www.accessmedicine.com/content.aspx?aID=2966145.