The reason callus develops is because of excess or unusual pressure in the affected area whilst a person is walking and/or standing. The increased pressure results in the body thickening the skin in this area. This happens on purpose as a protective layer between the ground or shoes and the skin, or over bony prominences.
Corns:
These are due to a small area of very high pressure, often with callus over the top of them. Tney can also be due to friction (for example, excessive sliding of the foot in shoes especially if the person has very dry skin). They can be very painful if they are deep enough to press on nerves in the skin.
There are several different types of corns:
Hard corn (Heloma durum) – These are usually on the sole of the foot, over bony areas and occasionally the tops of the toe joints. These present as a small, concentrated area of hard skin.
Soft corn (Heloma molle) – These are corns that are found between the toes. They are named because they are often moist and as a result are softer than corns found elsewhere on the feet.
Seed corn (Heloma millare) – These are small, relatively superficial corns that usually result from friction and dry skin. May appear anywhere on the sole of the foot.
Vascular/neurovascular corn – These corns have some degree of blood vessel and/or nerve involvement, and can bleed or be painful when reduced. These usually develop in areas that have been subjected to very high pressures over a period of time.
Both callus and corns are either taken down or removed with the use of a scalpel by a registered podiatrist. This is not painful, as it is only thickened layers of dead skin that are removed. Corns can usually be enucleated (have the core gently removed) to provide relief from pain. However, if the original cause of the pressure on the foot remains the same, the callus/corns will likely build up again.