A plantar wart, sometimes called a verruca, is a small skin lesion that resembles a callus or corn. It is found on the bottom of the foot or toes and is caused by the human papillomavirus (HPV).  The Human Papilloma Virus is a slow-growing virus that invades the skin in many different body parts. Another name for the bottom of your foot is the plantar aspect of your foot; for example, you “plant” your foot on the ground, so when warts occur on the sole of the foot, they are called plantar warts.

Corns and calluses occur only over pressure points, causing the skin to build up, whereas warts, being due to a viral infection, can happen anywhere. They can sometimes be difficult to tell apart. One way to tell the difference is that warts are painful if squeezed or pinched from side to side, whereas corn or callus are not. Warts also often have black specs of dried bold within the lesion.

The main difference between plantar warts and those that grow elsewhere is that they tend to “grow in” instead of growing out because they are on a weight-bearing surface. Often, what you see is just the tip of the wart, so when you take the dead skin off the top, you expose a much larger lesion. For this reason, plantar warts can be more painful and more challenging to treat than warts that occur elsewhere.

The virus that causes warts is common in our environment, and they don’t readily grow on intact skin, but if there is a break in the skin, like a very small scratch, the virus can get in and start growing. It is believed that areas of moist contact, such as around swimming pools and shared shower facilities, are where you can pick up warts. The virus only grows in the thick layer of the skin (epidermis) closest to the surface. It doesn’t invade the dermis, the deeper layer of the skin. However, the epidermis and the dermis are closely entwined, and the dermis under the wart grows extra blood vessels and nerves in response to the virus. Because of these nerves, the wart hurts when pinched, and the black spots are specks of dried-up blood because of the blood vessels within the wart. The virus particles can spread from the main wart and begin growing remote or satellite warts at a distance from the original wart. Warts are more common in children and people whose immune system is compromised.

There are various methods for treating plantar warts, all of which aim to destroy the lesion. Some treatment methods involve invoking an autoimmune response but are generally not used. Unfortunately, warts are unpredictable, and even the best treatment methods still have a reoccurrence rate of around 15%- 20%. If left long enough, warts can sometimes disappear without treatment. Treatment is recommended if the warts are painful or there is a risk of transmission to other people.

Self-treatment using wart paints, gels, and plasters, available over the counter from a pharmacy. Most require daily application. The wart also needs debridement of the dead layers that form so the medication can get to the wart.

Chemical cautery using salicylic acid paste is essentially the same method as that used in over-the-counter paints, except it is much stronger. It generally requires weekly treatment, where the wart is shaved back, and the paste or acid crystals are reapplied. Depending on the size and number of lesions, it will take several visits.

Freezing using liquid nitrogen or dry ice is best for raised lesions on the top of the foot. Plantar warts, because they “grow in,” mean that you have to freeze too much of the surrounding skin to get rid of all of the warts, which can be pretty painful and is often ineffective enough to destroy all of the wart.

Burning using electrocautery or laser is an option but can also be painful. Electrocautery is rarely used as it tends to leave a scar, which can be uncomfortable on the sole of your foot.

Swift Microwave is a relatively new modality that uses a targeted microwave to heat and destroy the virus. It has a relatively high success rate but can require multiple treatments and is quite expensive.

Falknor Needling is a technique used to treat warts, particularly plantar warts, which involves repeatedly puncturing the wart with a sterile needle to stimulate the body’s immune system to fight the virus causing the wart. It is performed under local anaesthesia.

Surgical Excision is an option that physically removes the wart using blunt dissection with a spoon-like instrument called a curette. This can be performed in the rooms using local anesthesia and does not require stitches, as we only dissect through the superficial layers of skin. Scars are minimal, and healing time is 2-3 weeks. Not all warts are suitable for surgical excision due to their size, number, or location, and is typically used when other treatment methods have failed.

All wart treatments involve some discomfort and inconvenience. There is no single best cure for warts, as all lesions differ. Warts in adults or immunocompromised patients are generally more difficult to cure than in children.