Plantar Warts: A Dermatologist Explains Why These Warts are Tough to Treat

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Now that it is autumn you may have fond memories of summer. Perhaps you went swimming with your family at the local pool or even tried the water slides at the amusement park. It felt good to go barefoot and get cool by the pool. Yet by the end of summer you may have noticed a hardened lump or callous growing on the sole of your foot or even on one of your toes. You might see little black spots within the hardened skin. This growth is starting to be quite bothersome as daily activities including walking are becoming painful when you put any pressure on this tender spot. Can you guess what this growth is? Okay so my title gave it away. If this description sounds familiar there is a good chance that you may have what is known as a plantar wart.

In order to see what plantar warts look like The Mayo Clinic has a good visual of this type of wart for you to see. They are actually very common and especially among children, teens, and people who have a weakened immune system. Plantar warts are caused by the human papillomavirus (HPV) which gets into your bloodstream via cuts or cracks in the skin. This virus loves wet and warm environments. So just imagine the prime environment of a water park or pool shower area where tons of people are walking around in their bare feet. I know about plantar warts from personal experience. I used to get them all the time. I would have my plantar wart frozen off to no avail. It would keep coming back until it finally disappeared on its own. As ugly as they may be, water shoes worn at the pool or water parks, kept my feet planter wart-free for many years.

We have asked Dr. Lawrence Green, our consulting dermatologist, to explain how plantar warts develop and why they are so difficult to treat.

Q: How does one get a plantar wart?** Dr. Green:** Plantar warts are caused by a virus that specifically likes to infect the skin. Wart viruses come from a family of over 80 like viruses that are specific enough to want to infect only certain types of skin ie. animal or human, or even human thin skin over thicker skin. Wart viruses are very sturdy and are found all over the environment. If you have a break in your skin and you come in contact with the type of wart virus that infects that type of skin, you're likely to get a wart. That said, for reasons unknown, certain people seem genetically able to fight off wart virus infection better than others.

Q: Are these types of warts different from others? Where are the most likely places on the body to develop a plantar wart and what do they look like?** Dr. Green:** Plantar warts are usually on the feet because the specific types of wart virus that cause plantar warts will only want to infect very thick skin like what is found on the feet. Planter's wart virus will not usually want to infect thin skinned areas such as the face or mouth, etc. Warts grow because through a broken area in the skin (like a cut), the virus intercalates with the DNA in the nucleus of the cells it infects. Once In the nucleus, the virus functions as a parasite, living off the nucleus and making our own DNA replicate new virus particles to infect adjacent cells nearby in the skin.

Q: How are planter's warts best treated? Is there a possibility that the plantar wart will come back after treatment?** Dr. Green:** Unfortunately, there currently exists no anti viral pill or cream that can specifically kill wart virus. The best we have is a vaccine against a few types of wart virus that prefer to infect genital skin. This is important though because genital wart virus can lead to cancer in women. For planter warts, any treatment is made more difficult because palm and sole skin is naturally so thick, it is very difficult to get a cream or any therapy through the skin deep enough to get all the cells that have been infected with wart virus. So, dermatologists are often left with trying to freeze infected skin to destroy the infected zone of skin and also try and engender an immune response in that area that will also try and kill off the wart. Most other therapies work similarly by either trying to destroy infected skin or somehow stimulate one's own immune system to rid itself of the infected cells. Because no therapy is that specific, and if just one cell among the thousands of infected cells is missed, the wart can recur.

Thank you Dr. Green

For more information about this topic please visit our informational page on the symptoms, treatment, and prevention of warts.