A Corn or a Wart?
By Dr. Joyce Tse

Many people may notice a hard spot on the bottom of their feet. Could it be a wart, or is it a corn? The spot is usually painful and sometimes affects normal walking. There are numerous myths for their existence, and various methods for getting rid of it. However, it keeps coming back! Let’s read on to learn more about them.

A corn (sometimes referred to callus) is abnormal thickening of the keratin layer on our skin, which is usually due to stimulation of the epidermis by intermittent or increased pressure. Therefore, we usually find corns over the weight-bearing surfaces, such as the ball of our feet, at the tip or knuckles of small toes, on the side of the big toe, or on the heel, etc… In some cases, corns are caused by irritation or trauma. However, in the majority of cases, there are faulty biomechanics. When we walk, our body weight may not be evenly distributed over the sole of our feet, but concentrated at certain areas, thus causing an increase in pressure.

On the other hand, common warts are infectious and caused by human papilloma virus (HPV), which may happen in different parts of our body, such as our hands and feet and, less often, elbows and knees. Warts are estimated to occur in up to 10% of children and young adults, with greatest incidence between 12 and 16 years of age. Although warts will spontaneously clear after 2 years without treatment in 40% of children, they can also continue to increase in size and spread across the skin surface.

Human papilloma virus (HPV) can get on the feet!

There are over 60 strains of the human papilloma virus (HPV). The “cutaneous” HPV types, such as HPV types 1, 2, 3 & 4 cause common skin warts. Other strains of HPV may lead to warts on other mucous membranes, such as oral, anal, or genital cavities. Fortunately, cutaneous HPV types do not usually cause genital warts and are not associated with the development of cervical cancer. When warts happen on the sole of the feet, they are called “plantar warts,” which can be itchy or slightly tender.

What should I do if I got them on my feet?

First of all, one must distinguish a wart from a corn. Warts are infectious and have an entirely different treatment regimen! Look carefully into the spots on your feet. Your skin lines should go through a corn or callus, but go around a wart. Corns or calluses happen on areas with excessive pressure, but warts can appear anywhere on your feet. Generally, corns have a hard center and solid yellow surface, while warts have a cauliflower-like surface and are typically slightly raised above the surrounding skin. If the spots are spongy and pale in the center, or if you noticed the little black dots (they are blood capillaries), the likelihood of wart is much greater.

To treat a corn, you can try Epsom salt soaking with pumice stone filing and skin moisturizer. Medically skilled paring of the corns and topical keratolytics are recommended. In addition, the underlying etiology (i.e. biomechanical/weight distribution property) must be identified to determine the reason for the excess pressure over the area. Your podiatric doctor can help you in this aspect with proper padding, cushioning, or custom orthoses that can help redistribute your weight as you walk. This will reduce the pressure and thus reduce the corn formation over the area. 

If the suspicion for wart is high, you may try the following DIY method. The idea is to suffocate the virus and the surrounding skin; the lack of oxygen speeds the degeneration of the wart. Cover the wart(s) with some duct-tape cut slightly larger than the surface area of the wart, care must be taken to ensure the skin does not breathe for long periods between fresh dressings, and effective results should be noticeable within couple weeks, or else be discontinued.

Watchful waiting is discouraged due to the significantly increased likelihood of passing on the virus to another skin surface. In some cases, the body’s own immune system will attack and kill the wart, which will turn black and fall off, although this may take two years or longer. If you have any doubt, you should see your podiatric doctor. The medical treatments include keratolytics, hyperkeratoses debridement, and cryosurgery (freezing). In severe cases, laser therapy or surgical excision may be indicated.

This article was submitted by Dr. Joyce Tse of California Foot and Ankle Medical Center. Feel free to call 2525 0611 for more information or to make an appointment.