Calluses on the foot are areas of hard, thickened skin. When the skin gets hard and thickened in certain areas, it tends to take on a yellowish appearance. Calluses are usually found over the areas of the foot that rub on things, causing a chronic mechanical injury. The skin reacts to this by thickening – it does this as a form of protection. If the skin stayed thin, it might be damaged – by thickening it adds a protective layer of skin over the area.
Calluses tend to be found in the areas of the foot where the skin rubs between a bony prominence on the inside and footwear on the outside. Apart from the rubbing of the foot on footwear, there can also be mechanical stresses in “foot to ground” contact and also “toe on toe” rubbing.
Corns and calluses may be a sign of abnormal foot function. They can be caused by abnormally high stresses and loads being put through that area of the foot. This irritates the skin, causing it to thicken – and hence the callus or corn appears.
The common areas to get calluses are:
Corns are basically the same as calluses but with an extra feature. Calluses are called corns when the centre becomes hardened – this central area being harder to the touch than the rest of the callus. This central hardened area occurs at the point where most of the pressure that is causing the corn to be formed has been focused.
Sometimes it looks the same colour as the rest of the corn and therefore in these situation, can only identified by touching. In some corns the central area can be white or some other discoloration may be seen.
There are different sorts of corns. The commonest ones found are called:
Hard corns are formed in areas where mechanical pressure and stresses has been focused on the skin, causing the classic sort of corn that is described above.
Just as the name suggests, soft corns are softer to the touch than hard corns. They are found between the toes, usually in the gap between the fourth and fifth toes. They are started by the same pressure or mechanical stresses that causes the skin to go hard, just like the hard corns. Then moisture from sweat collects and macerates the skin, making the thickened hard skin go softer and turn white.
Soft corns are often be quite a bright white colour, and as it is found between the toes, it is often confused with athletes foot which is a fungal infection.
These slightly stranger corns look like a their name, like little seeds, on the skin of the foot. They are found around the edges of weight bearing areas of the foot. They are usually found by themselves, although they can occur in clusters. They are more commonly found in people with dry skin – a condition called “anhidrosis”.
There are sub-ungal corns, which are corns found beneath the nails, on the nail bed. There are also fibrous corns and vascular corns. An expert podiatrist will be able to identify these rarer sorts.
Before thinking of treating the callus or corn, a podiatrist will assess the foot to try to identify why the callus or corn has been formed in the first place. This may be something simple, such as badly fitting shoes, but it may also indicate abnormal function of the foot during the walking process. This can be addressed in several different ways depending on the findings.