One of the questions that we are asked often as podiatrists is the difference between a corn and a callus…. This is closely followed by what’s the difference between a corn and a wart???
Well, they are similar and also very different! The similarities is that they all generally involve hyperkeratosis of some kind which is basically hard toughened skin. But the causes behind them are different.
Lets start with a wart or verruca. A wart is a virus. It is actually the human papilloma virus that gets in between the layer of skin that has died (the outerlayer) and the inner layer of skin. It virus successfully invades the skin cell before it dies changing the makeup of the cell and so forming a wart. Warts on most parts of the body sit above the skin level however on the bottom or plantar surface of the foot they are pushed inwards under pressure and are known as plantar warts. There is a round patch in the centre often with a blood supply and hard skin in callus forms around or on top of it. A wart can appear on its own or in a pattern known as a mosaic wart. The virus survives on the bottom of the foot and the only way to get rid of them is to stimulate the patient’s immune system to expel the virus. More about this in upcoming blogs!!!
Callus and corn are actually related in that all corns start life as a callus. A Callus is an immune system response to pressure. This pressure can be from shoes, the ground, fat pad erosion and many other factors. The bodies response to this pressure is to try to protect the area. It generally will lay down more skin in the affected area to try to cushion the structures involved. However, skin has poor cushioning properties and as pressure builds more and more skin is laid down. Skin is made of a substance known as keratin. It is the same material that hair and nails are made from. Too much skin is known a hyperkeratosis. Hyper from the Greek meaning excess and keratosis, the product that skin is made from. This hyperkeratosis dries and thickens over time until you generally end up with what we would call a callus. This skin is dead and is usually pared away from the healthy viable skin by a podiatrist to reduce pressure.
If this callus is not reduced, generally its hardness means that pressure will continue to build in the area. At certain points in the callus small points of pressure will compress and further harden the callus until a corn forms. Corns can be soft corn which occur between the toes, hard corns on the plantar surface and sometimes subungal corns can occur under the nail. The corn has a central core or keratin which some people refer to as a ‘plug’. This is often pushed by the continuing pressure onto internal structures of the foot causing extreme pain, especially when pressuring a nerve. These are often quickly and easily removed and a skilled podiatrist should be able to do this with minimal to no discomfort to the patient. The patient will feel instant relief and generally can get on with their day 100% pain free.
Corns can be found in just about every part of the foot from between the toes and tops of the toe knuckles to the plantar surface. Some people choose to buy medicated corn pads to remove the pain. These have a pad coated with salicylic acid that slowly eats away the corn’s core, however in many cases the corn pad is either too large for the affected area or has been left on too long and the healthy skin surroundings the corn is also damaged. NO PATIENT WITH DIABETES SHOULD EVER USE MEDICATED CORN PADS!!!! They cause damage to the skin far too easily and have been known to cause ulceration. More often than not a 20 minute consultation with your podiatrist will remove these problems and improve your pain immediately! Don’t put up with the pain. Make an appointment today!