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By Nancy Sokoler Steiner

You don’t remember bumping into anything, but there it is: A big, angry-looking purple bruise on your forearm. How did it get there, and why do bruises like that seem to be popping up on your arms and legs more frequently as you age?

“These kinds of bruises, referred to as solar purpura, may start occurring in your 50’s, and become more common as time passes,” says David E. Sawcer, MD, PhD, Assistant Professor of Clinical Dermatology in the Keck School of Medicine at USC. “They happen closer to the surface of the skin than other bruises, and are not usually caused by trauma.”

Bruises come from injury to the small blood vessels (capillaries) near the skin’s surface. Blood leaks from the capillaries and remains trapped under the skin. Normal bruises are usually tender, change colors, and go away after a week or two. Solar purpura, on the other hand, don’t hurt, and often get darker, progressing from red to deep purple before they fade. They can take several weeks to disappear.

Why it Happens

As our skin ages, its structure begins to weaken. The outer skin layers grow thinner and the capillary walls become more fragile. At the same time, the layer of fat under the skin thins, providing less padding and insulation.

“Day-to-day activity is enough to cause solar purpura,” says Dr. Sawcer. “The capillaries in the skin are more easily damaged because they become thinner and less protected.”

Although bruising can’t be avoided, sun exposure worsens it by weakening the skin. Also, blood-thinning medications, such as Coumadin and aspirin, contribute to bruising by slowing the blood’s ability to clot. Corticosteroids, prescribed for a variety of conditions including rheumatoid arthritis and asthma, cause thinning of the skin, which also promotes bruising.

On rare occasions, bruising may indicate medical conditions such as clotting or coagulation disorders. If your bruises are painful, you experience abnormal bleeding in other areas, or you start bruising when you’re ill, be sure to see your physician. If you see bruising on a loved one and worry about physical abuse, you should know that bruising caused by abuse tends to appear on different parts of the body -- such as the face, neck, back and chest – rather than on the hands, arms and legs. Still, it’s a good idea to talk to your loved one if you have any concerns.

What Can You Do

Sun exposure makes the skin weaken more quickly, so protecting yourself from the sun can help delay this process. Keeping skin well moisturized can also lessen bruising. Do both at one time by using a moisturizer with sunscreen.

The most effective treatment for bruises is time. Eventually, the body reabsorbs the blood, and the bruise disappears. Cosmetics may help hide bruises in the meantime.

“People tend to be concerned about bruises because they’re deeply colored and look serious,” says Dr. Sawcer. “But despite their appearance, they’re generally not something to worry about.”

Labels: Aging, Bruise, Bruising, Feature Articles, For the Body, Healthy Aging, Nancy Sokoler Steiner, Skin, Solar Purpura