Corn: Description
A corn (clavus, crow’s eye, light thorn) is a roundish, sharply defined thickening of the skin. In the center sits a hard, pointed corneal cone that extends into deeper layers of the skin and causes pain when pressure is applied.
Corns are very common. Women, rheumatism and diabetes patients are particularly affected.
Where and how do corns develop?
Corns are caused by permanent pressure or friction on the skin. The cause can be, for example, shoes that are too tight or a foot malposition.
The constant pressure initially causes a callus to form on the foot. The uppermost layers of skin thicken and keratinize, forming a protective cushion against the constant external pressure. Over time, this increased keratinization (hyperkeratosis) extends into deeper layers of skin – a central, keratinized thorn develops.
Different types of corns
Doctors distinguish between different forms of corns, but in practice they cannot always be precisely distinguished from each other. Different types of corns may require different therapies.
- Clavus mollis (soft corn): Found between very tightly packed or deformed toes and has a soft, flat core.
- Clavus durus: A corn with a hard, highly condensed corneal core. Forms most often on the outer foot.
- Clavus subungualis: A corn under the nail.
- Clavus vascularis: A corn in which there are blood vessels. That is why it often bleeds when removed.
- Clavus neurovascularis: A corn interspersed with nerves and therefore very painful.
- Clavus neurofibrosus: A very extensive corn. The sole of the foot and the ball of the foot are preferentially affected.
- Clavus miliaris: It is a peculiarity among corns. It is a large number of small, non-deep, round cornifications that resemble corns and occur mainly in areas that are not exposed to pressure. Since there is no pain with a clavus miliaris, it is also called a pseudo corn.
Corn or wart?
Corns and warts can be similar to each other. However, the experienced podiatrist or doctor will immediately recognize the difference.
Warts, like corns, develop in areas that are exposed to strong mechanical stress. The most common type is the plantar wart, which is usually located under the cornea and contains small black spots or dots. These are dried hemorrhages. Unlike a corn, warts do not have a corneal wedge in the center and affect only a few layers of skin, so they tend to be flat.
Corn: Symptoms
A corn appears as a roundish, sharply demarcated thickening of the cornea, which – due to the thick corneal layer – appears yellowish. It is about five to eight millimeters in size.
In the center of the clavus sits a thickened horn (keratin cone) that extends funnel-shaped into deeper layers of the skin and causes pain when pressure is applied. A small corn is initially only uncomfortable when walking; larger corns, on the other hand, can cause severe pain and limit the mobility of the affected person to such an extent that it can lead to occupational disability.
The tissue around the thorn can change. Sometimes fluid accumulates (edema) or inflammation develops.
If the corneal cone presses on a joint, it can fuse with the area around the joint capsule and cause periosteal irritation or inflammation.
Corn: Causes and Risk Factors
A corn develops when skin stretched over a bone is permanently exposed to high pressure or friction. The most common cause is wearing shoes that are too tight. Especially tight, squeezing shoes like high heels or tight shoes made of hard leather like pointed boots are dangerous. For this reason, women also have corns more often than men.
Socks that rub on the skin can also cause a corn.
Deformities of the feet and toes also promote the development of corns. Deformities such as hallux valgus, hammertoes or bony outgrowths (exostoses) put increased stress on individual areas – a corn on the foot forms.
Especially in diabetic patients, a corn is a potential entry point for germs and must therefore be treated with particular care.
Corn: examinations and diagnosis
A doctor or experienced medical chiropodist (podiatrist) can usually recognize a corn right away by its appearance. The keratin cone can be identified with a magnifying glass.
A corn must be distinguished from a wart: the latter can also have excessive keratinization (hyperkeratosis). The very common plantar warts, however, can be distinguished from a corn by the brown dots and bluish-blackish, stripe-like deposits in their center.
Corn: Treatment
In order to successfully treat a corn and avoid a relapse, not only the clavus itself, but also – if possible – its cause must be eliminated. Basically, the following options are available for the treatment of a clavus:
Corn plaster
Especially in the case of a corn under the foot, however, the use of corn plasters is not without danger, as they can easily slip. The acid on the patch then penetrates the thin, healthy skin next to the corn, where it can cause injuries and inflammation and promote infections. Diabetics (are very susceptible to foot infections), people with circulatory problems and those with thin, brittle or cracked and dry skin should be particularly careful. Experts advise them against self-treatment with a corn plaster.
Salicylic drops
As an alternative to the corn plaster, drops containing salicyl can be used. They are applied according to the pharmacist’s instructions or the package insert for several days. After that, the softened callus can usually be removed without any problems. A hot foot bath facilitates the removal. To protect the healthy skin, it can be covered with cream.
The best way to remove a corn is by a doctor, an orthopedist or a medical foot care professional (podiatrist). First, the callus is softened in a hot foot bath. Then, using a suitable instrument (such as a cutter, scalpel), one removes the excess layers of skin. Hydrogen peroxide is used to soften the core. If the keratin cone is particularly deep seated, it may also be necessary to treat it for several days with a cornea-dissolving substance. A particularly deep-seated corn is surgically removed.
After clavus removal, the affected area should be protected from pressure by foam rings or inserts.
Under no circumstances should you attempt to use knives or other devices to cut out the corn yourself. The risk of injury and serious infection is too high!
Read more about removing corns in the article Removing Corns.
Cause removal
- Refrain from wearing shoes that are too tight and rubbing.
- During treatment, the area can be surrounded with small foam rings (corn rings) to relieve pressure. This is also useful during the initial period after surgery. Silicone or foam inserts in the shoe, cotton socks or shoes made of soft materials can provide additional relief.
- Regular washing and creaming keep the skin healthy and resistant.
- If a foot malposition is the cause of corns, orthopedic insoles, orthopedic shoes or other orthopedic aids can provide relief.
In some cases, a foot malposition is eliminated by surgery. The orthopedist decides whether such an operation is useful or whether orthopedic insoles are sufficient.
Corns in children
Corn: course of the disease and prognosis
Every corn can be removed completely. The sooner a corn is recognized and treated, the better and faster the healing process will be. If a corn is removed by hand with a knife, scars may remain.
Complications
Especially in cases of nerve damage due to diabetes mellitus (diabetic neuropathy), patients may not feel any pain. Especially in such cases, a corn can cause serious complications because the problem is recognized too late or underestimated by the patient. Connecting ducts between the skin and an organ (fistulas) or an ulcer may form. Infections can cause tissue on the foot to die (diabetic gangrene).
