Skincare science: Skin damage

Aging and sun exposure results in skin damage and characteristic changes in skin structure. Usually, the damage is not uniform, and some areas of your skin will start behaving differently than the surrounding areas. This week I wanted to write about the most common changes seen in damaged skin. It’s worth understanding these changes — it will allow you to more critically evaluate the promises that skincare and skin treatments routinely make. Now keep in mind that there is an entire medical specialty (Dermatology) devoted to the study and treatment of the skin, so this list just scratches the surface.

Skin irregularities fall into a few general groups:

  1. Contour changes
  2. Blood vessel changes
  3. Benign growths
  4. Pre-cancers and cancers

It’s also worth realizing that some of these skin changes are more dangerous than others, and unfortunately, the appearance may not correlate with the danger. For example, the appearance of seborrheic keratosis may bother you a lot, but they aren’t particularly dangerous. On the other hand, a melanoma is very dangerous, but most people are likely to not even notice it.

A wrinkled faceWrinkles aren’t very dangerous



Also called “rhytids.” Wrinkles are formed by a fairly complex series of changes in all layers of the skin. When you compare a wrinkle to the normal skin just next to it, you can see several differences.

  1. The epidermis is thinner (except for sun-exposed epidermis, which is actually thicker).
  2. The border between the epidermis and dermis is flattened.
  3. The dermis is thinner and weaker. The abnormal increase in dermis proteins found in sun-exposed skin is actually reduced under a wrinkle.
  4. Finally, the hypodermis is thinner as well.

All of these changes combine to make a depression in the skin, forming a wrinkle.


This is the dimpled, lumpy-bumpy skin on the buttocks and thighs, which occurs more often in women. It is caused by an abnormal arrangement of the fat cells in these areas. We don’t yet definitive know what causes cellulite. There are several theories though:

  1. The blood supply to the fat cells may be compromised, causing the tissues around them to become hardened and scarred.
  2. The dermis weakens and stretches with aging, but the strong fibrous bands that divide the fat cells into groups (like the stitching of a quilt) remain strong. So as more fat is deposited, each square of the quilt pooches out, but the intervening stitching doesn’t, causing dimples.

Regardless of which theory is correct, two things seem to be true: cellulite is caused by fat deposition (and will decrease if you lose weight), and it is associated with estrogen (female hormones).

Blood vessel changes


Telangectasias are commonly called “spider veins” or “broken capillaries.” They’re abnormal blood vessels—tangled and floppy, like a bundle of old stretched out socks. These aren’t technically changes in the skin itself, but they do show up as color changes on the skin. They are thought to form in response to long term exposure to UV light. There are other common reasons why you might get telangectasias—like pregnancy, chronic alcohol use, or rosacea. More rarely, telangectasias can be a marker for a more serious illness like scleroderma, CREST syndrome, and lupus.

Angiomas are sometimes cherry-colored


Angiomas are overgrown blood vessels in the skin. There are two common types. Cherry angiomas are small cherry-colored spots that tend to appear on the trunk in people over age 40. Spider angiomas appear on the face and chest, and have a central spot with spider-like blood vessels entering it. They are common in pregnancy, but can occur in children and adults of both sexes.

Varicose veins

These are abnormally widened veins, usually found in the legs. Your blood pressure is higher in your legs, which stretches out blood vessels, and leads to varicose veins. They are located deeper under the skin than telangectasias, because that’s where these larger veins live. They’re bluish because they’re returning deoxygenated blood to the heart.

Benign growths

redhead with frecklesFreckles aren’t dangerous either


These are small islands of skin containing overactive melanin-producing cells. Each “island” is only a few millimeters in size (a tenth of a centimeter). The cells are present from birth, but the color difference only shows up with sun exposure. Freckles fade away in winter and darken in the summer as you get more sun. They usually appear on the face, arms, and shoulders.

Solar lentigo

Also called age spots or liver spots, these appear on sun-exposed areas of the skin. They are areas of skin containing a greater than normal number of melanin cells. Contrast this with freckles, where the skin has a normal number of melanin cells. Usually, once it’s formed, a solar lentigo won’t go away, even if you stay out of the sun. Solar lentigo can be the precursor of a benign growth called seborrheic keratosis. Unfortunately, solar lentigo can be difficult to distinguish from pre-cancerous types of growths like lentigo maligna (which can turn into melanoma). Melanoma is a particularly dangerous type of skin cancer. So the bottom line is that if you develop a new, dark spot on your skin, more than a few millimeters in size, you should see your doctor or dermatologist.


Warts are caused by a viral infection (Human Papilloma Virus – HPV) that results in an overgrowth of skin cells, and a bumpy/rough appearance. They are exceedingly common, and not very dangerous. They can be confused with seborrheic keratosis.

Seborrheic keratosis

These waxy bumpy growths can grow out of solar lentigines, or just show up unannounced. They are dark and have a rough texture, and look a bit like a raisin stuck on to the skin. They’re not dangerous, but they don’t look great. SKs (as they are called) tend to start making an appearance in the 50s and 60s, and can appear even in areas that don’t get much sun exposure.

Pre-cancers and cancers

Dysplastic nevus

Basically an abnormal mole, which is large (over 5mm), has an irregular blurry margin, and multiple colors and textures. In addition, dysplastic nevi look abnormal when their cells are examined under a microscope. Not all dysplastic nevi will become cancer, but some of them can turn into melanoma. Further, someone who has five or more of these abnormal moles has a much higher chance of developing melanoma somewhere else on the skin!. So if you have moles, you should examine them regularly, and see your doctor if you suddenly have a new mole or an old mole has changed in appearance.

Actinic keratosis

This is an area of abnormal epidermis that has become rough, scaly, and reddish. It is closely associated with exposure to UV light. This is also a pre-cancerous skin change— there is a chance that it will become a type of skin cancer called squamous cell carcinoma. About 1 in 50 of these spots can become a cancer after four years. Actinic keratosis is very common, and very easy to treat.

Basal cell carcinoma

The most common skin cancer, and also the least dangerous. Basal cell carcinomas (BCCs) often occur on sun exposed areas of the face like the nose, cheeks and ears. They can sometimes have a telangiectasia on top. If they are caught quickly and treated, they are relatively easy to remove.

Skin spotsA leopard’s spots aren’t cancerous…

Squamous cell carcinoma

More uncommon than BCC, and much more dangerous, squamous cell carcinoma develops from the cells of the epidermis. SCC grows over weeks to months, and can be tender and even form ulcers. It can develop from an actinic keratosis, and usually occurs on sun exposed areas of the face, or the shoulders, back, or legs. This needs to be treated quickly and aggressively, as it can be life-threatening.


The most dangerous of the skin cancers, and fortunately the most uncommon. Melanoma is a cancer of the pigment cells of the skin (melanocytes). The problem with melanoma is that it often doesn’t look like much – it can masquerade as a mole and hide in plain sight. It also tends to spread silently to other parts of the body. Melanoma is very closely associated with exposure to UV radiation—whether it is from sunlight or a tanning bed. I can’t emphasize enough how important it is to wear sunscreen and avoid tanning beds—this will reduce the aging effects of UV light, and reduce your risk of cancer. In addition, if you have moles, you should be examining them regularly, and you should see your doctor if you develop new moles or changes to existing ones.

Next week

Next week we’ll take a look at the many available treatments that promise to reverse the signs of skin aging: skin care products, injectables, peels, lasers, and so on.


1) Br J Dermatol. 1990 Apr;122 Suppl 35. Pigmentary changes of the ageing skin. Ortonne JP
2) J Invest Dermatol. 1998 Nov;111(5). Molecular regulation of UVB-induced cutaneous angiogenesis. Bielenberg DR, Bucana CD, Sanchez R, Donawho CK, Kripke ML, Fidler IJ.
3) Am Fam Physician. 2009;79(2). Common Pigmentation Disorders. Plensdorf, S, Martinez, J
4) Br J Dermatol. 1999;140(6). A histological study of human wrinkle structures: comparison between sun-exposed areas of the face, with or without wrinkles, and sun-protected areas. Contet-Audonneau JL, Jeanmaire C, Pauly G.
5) J Am Acad Dermatol. 2006 Jul;55(1). Photoaging: mechanisms and repair. Rabe JH, Mamelak AJ, McElgunn PJ, Morison WL, Sauder DN.