Calluses are created in response to pressure and/or shear force in the skin over bone prominences in the foot. Calluses are created to protect the skin from breaking down and causing open wounds. As humans developed, this was an important to reduce the risk of open wounds. There are different types of calluses tylomas, porokeratosis, plantar warts (plantar verrucae), and intractable plantar keratosis are the most common. Rarely, a very dangerous tumor can mimic a callus. Amelanotic melanomas can be fatal and have been misdiagnosed by experienced physicians. If a lesion suddenly appears, changes by growing in size, changing in color, ulcerating, and or has borders becoming irregular, it needs to be addressed by an experienced doctor and biopsied. It is important you let your physician know of any changes, take pictures, it is easy to take a quick picture so your physician has a reference point.
Tylomas are one of the most common types of calluses often in seen in athletes. This type of callus is characterized by uniformly thickened skin over areas on the ball of the foot, heel, or other pressure area of the foot. This type of thickened skin lesion is caused by shear force. Shear force is the rubbing the skin between a bone and an object of pressure. Occasionally, tylomas will become very hard, crack, bleed, painful, infected, blister, or form fissures.
The key to callus treatment is reducing the thickness of the skin, this can be done with exfoliating creams or manual debridement or thinning of the skin. Some tylomas may have skin folds associated with them making them difficult to debride, others may be very hard, here are some trick we tell our patients.
- Soak the area to be trimmed or trim the area while in the shower.
- Treat the area with an exfoliating cream before trimming.
- In severe cases or cases of heel fissures apply a strong exfoliating cream like Kera 42 at night, put a plastic bag over the foot then a sock.
- Apply a strong exfoliating cream like Kera 42 multiple times a day until the desired results, then use a daily cream like Kamea 20 or Urea Care.
Intractable Plantar Keratosis (IPK)
Intractable plantar keratosis or IPK’s are similar, but, bit different than tylomas. Intractable plantar keratosis are caused by pressure from bones or bone spurs. IPK’s have a core present that usually communicates with the bony projection. The bony projections can be caused by arthritis, lack of a fat pad on the foot, prominent bones, or a fracture that did not heel properly. These types of skin lesions are extremely painful especially when walking, patients commonly tell me it feels as if there’s a pebble in their shoe. These are very difficult to trim or debride correctly. IPK’s are commonly misdiagnosed as plantar warts. Many times patients come into the office after being told they have a plantar wart when in fact it is an intractable plantar keratosis. This is a real problem because the treatment for these two lesions are very different. As you’ll find later viruses are treated by destroying the actively growing skin cells to kill the virus. This can cause scar tissue to form, scar tissue over the ball of the foot can become very painful and lead to further complications.
IPK’s are treated by debridement, offloading, exfoliating creams, and padding techniques conservatively and by resection of the bony prominences surgically.
Porokeratosis are very similar to intractable plantar keratosis, however, the cause of porokeratosis have yet to be determined. Porokeratosis are not associated with any particular type bony prominence, structure in the foot, or virus. They look much like IPK’s but they can occur anywhere on the bottom of the foot. There is a core with surrounding thickened skin. There is no black dot present as there is in plantar warts. Some doctors believe porokeratosis are related to foreign bodies that have penetrated into the dermis of the skin causing the skin to produce a protective deposit of skin. Porokeratosis can appear as a single lesion or multiple lesions over any part of the foot on the plantar or bottom of the foot. People describe the discomfort as if there were several pebbles stuck to the bottom of their foot or in their shoe. Porokeratosis can become very painful over time depending on the location.
Several different treatments have been attempted over the years including injections into the base of the lesions with dehydrogenated alcohol, debridements, and exfoliating agents. Debridement can be painful, but often gives immediate relief when done correctly. In order to debride porokeratosis correctly, it is important that the core of the lesion is removed. Using a pumice stone or other abrasive material only removes the outer surface not the core. Minimal relief is achieved from this type of debridement.