Corns and warts are quite common and two of the more frequent conditions that podiatrists treat on a daily basis. They can be quite similar in their presentation but they are actually quite different in terms of what causes them and how they are treated so it’s important to know one from the other.
Corns are actually related to callous so let’s start there. Callous is formed as an immune system response to pressure. This pressure can come from a variety of sources such as footwear, the ground, how we walk and the actual structure of the foot. The body’s response to this pressure is to create more skin which in turn creates more pressure…I think you can see where this is going! This excess build-up of skin is called hyperkeratosis and it becomes dry and thick and eventually forms a callous. Callous is usually not painful but can lead to cracks (fissuring) which can be a portal of entry for bacteria. A corn is created when an area of callous is not taken care of. Pressure continues to build and it creates a focal point which is where the corn forms. Corns can develop in between toes, on the tops of toes, under the foot and even under toenails.
Corns have a central core (sometimes called a plug) which grows inwards due to continuing pressure and can become quite painful, especially if it starts to push against a nerve. A corn will often be rounded and have fairly defined borders. The natural lines of the skin continue over the corn and it is most sore when pushed upon. A wart, or plantar wart as they are known on the feet, is something entirely different. Plantar warts are caused by a virus known as the human papilloma virus. This virus invades the skin cell and changes its structure to create a wart. It is the same virus that causes warts on other parts of the body, however, when they form on the feet warts tend to be pushed inwards due to pressure.
Like corns, plantar warts can be extremely painful but unlike corns, they are not dead skin and they have an excellent blood supply. Plantar warts present similarly to corns, however, they can be more poorly defined and can have a ‘cauliflower’ appearance. The normal skin lines become interrupted and plantar warts are more tender if you squeeze the borders rather than pushing directly on them.