Ask the doctors 8/13

Dear Doctors: I run a lot and developed a growth on the knuckle of my second toe. It’s hard, with a sharp point in the middle, and it hurts. My running coach says it’s a corn. I thought only older people got those. Will it go away on its own?

Dear Reader: A corn is a small, round area of thickened and hardened skin. Those that form on the top of the foot, typically in the bony regions of the toes, are known as hard corns. Soft corns, which have a pliable surface and a springy, almost rubbery, texture, form between the toes.

Corns can also occur on the bottoms of the feet. These are typically quite small, with a seedlike appearance that gives them their name. This type of corn often appears in clusters. When seed corns develop on the weight-bearing portion of the foot, they can be quite painful.

As with a callus, corns form because the skin has sustained repeated damage from pressure, friction or both. This often results from footwear that is too tight or fits poorly. To protect itself from further injury, the skin develops a physical barrier made up of tougher cells. Corns are different from calluses in that they are smaller and deeper. Calluses can develop anywhere, but corns only occur in areas where a bone exerts pressure on the skin.

Unlike calluses, corns are often tender or painful. This is due to their central core, which is the sharp point that you described. It forms around the area of damage that the skin is trying to protect.

It is true that corns become more common as we get older. This is often due to the age-related physical changes that take place in the foot and in the gait, which can then affect the fit of someone’s existing shoes or socks. Osteoarthritis can also affect the bones of the foot and lead to corn formation.

Corns don’t go away on their own, so it’s important to take steps to mitigate them. Untreated, they can get infected and have an adverse effect on posture, gait and alignment. Begin by assessing your footwear. Shoes that are too loose or too tight can cause the pressure and friction that cause corns. So can long toenails. As a runner, you might check if something in your stride or foot placement has changed.

To treat a corn, soften the area daily in warm water, then gently rub with a pumice stone. Only remove the topmost layers of dead cells each time, as taking too much can damage healthy skin. Use moisturizer to keep the area soft, and protect it from further damage with doughnut-shaped corn pads. These are available at drugstores. Corn-removal products, which use salicylic acid to thin the skin, can be effective. However, they are not recommended for anyone with poor circulation.

If a corn doesn’t respond to treatment, see your health care provider. Never try to cut or shave a corn, as this can lead to a serious infection.

Send your questions to askthedoctors@mednet.ucla.edu.