Corns and calluses
CORNS AND CALLUSES
CORNS AND CALLUSES DEFINITION
Corns and calluses are thick, hardened layers of skin that develop when your skin tries to protect itself against friction and pressure. They most often develop on the feet and toes or hands and fingers. Corns and calluses can be unsightly.
If you’re healthy, you need treatment for corns and calluses only if they cause discomfort. For most people, simply eliminating the source of friction or pressure makes corns and calluses disappear.
If you have diabetes or another condition that causes poor blood flow to your feet, you’re at greater risk of complications from corns and calluses. Seek your doctor’s advice on proper care for corns and calluses if you have such a condition.
CORNS AND CALLUSES CAUSES
A callus, or callosity, is a section of skin that has become toughened and thick as a result of friction, pressure or irritation. If the friction (rubbing) is excessive, blisters will form rather than calluses. Calluses on feet are most commonly caused by frequent walking. In general, calluses are not harmful, but may occasionally lead to infections or ulcerations of the skin.
A corn, clavus (plural: clavi) is a specially-shaped callus of dead skin. It usually forms on hairless and smooth (glabrous) skin surfaces, especially between the toes or fingers.
Corns and calluses generally form when the skin tries to protect an underlying area from injury, pressure or rubbing. They are not usually painful, but can become sore if they grow.
Corns and calluses affect women more commonly than men, as well as people who wear ill-fitting shoes, individuals with sweaty feet, and those who have to stay standing for long periods each day. Corns and calluses are also more common among people with foot problems, such as hammer toes or bunions.
A corn will most typically develop on the top and side of the toes – its inside may be either soft or hard. Hard corns are common; they tend to be small and occur in areas of firm, hard skin – areas of thickened skin or calluses. Bony areas of the foot are favorite sites for hard corns. Soft corns tend to be whitish in color, and have a rubbery texture – they more commonly occur between the toes (areas of moist and sweaty skin).
Calluses are yellowish or pale in color; they feel lumpy to the touch. However, as the skin is thick it may be less sensitive to touch compared to the skin around it. Calluses are often bigger and wider than corns, and do not have such defined margins (edges). Calluses commonly appear where the skin frequently rubs against something, such as a bone, some item of footwear, or the ground. They typically form over the bony area just under the toes – areas of skin which take the person’s weight when they are walking.
CORNS AND CALLUSES PATHOPHYSIOLOGY
Corns are the result of mechanical trauma to the skin culminating in hyperplasia of the epidermis. Most commonly, friction and pressure between the bones of the foot and ill-fitting footwear cause a normal physiological response—proliferation of the stratum corneum. One of the primary roles of the stratum corneum is to provide a barrier to mechanical injury. Any insult compromising this barrier causes homeostatic changes and the release of cytokines into the epidermis, stimulating an increase in synthesis of the stratum corneum. When the insult is chronic and the mechanical defect is not repaired, hyperplasia and inflammation are common. With corns, external mechanical forces are focused on a localized area of the skin, ultimately leading to impaction of the stratum corneum and the formation of a hard keratin plug that presses painfully into the papillary dermis, which is known as a radix or nucleus.
A callus is a local thickening of skin, characterized by accelerated keratinization and a reduced rate of desquamation. Expression of cornification-related molecules, including involucrin, filaggrin, caspase 14, and calcium-sensing receptor, are higher in the anterior aspect of the heel. Expression of adhesive proteins such as corneodesmosin, desmoglein 1, and desmocollin 1 are also increased in the heel. Protease-activated receptor 2 expression is reduced in the stratum granulosum in the heel. The number of proliferating cells in the stratum basale is significantly increased in the heel compared with other areas of the foot. Therefore, calluses are proposed to form as a result of hyperproliferation and incomplete differentiation of epidermal keratinocytes and increased expression of adhesion molecules.
CORNS AND CALLUSES SYMPTOMS
You may have a corn or callus if you notice:
- A thick, rough area of skin
- A hardened, raised bump
- Tenderness or pain under your skin
- Flaky, dry or waxy skin
Corns and calluses are not the same thing.
- Corns are smaller than calluses and have a hard center surrounded by inflamed skin. Corns tend to develop on parts of your feet that don’t bear weight, such as the tops and sides of your toes and even between your toes. They can also be found in weight-bearing areas. Corns can be painful when pressed.
- Calluses are rarely painful. They usually develop on the soles of your feet, especially under the heels or balls, on your palms, or on your knees. Calluses vary in size and shape and are often larger than corns.
CORNS AND CALLUSES DIAGNOSIS
The GP (general practitioner, primary care physician) will interview the patient and ask about his/her lifestyle. The patient’s footwear may also be checked. There will be a physical examination.
CORNS AND CALLUSES TREATMENT
Treatment for corns and calluses usually involves avoiding the repetitive actions that caused them to develop. You can help resolve them by wearing properly fitting shoes, using protective pads and taking other self-care measures.
If a corn or callus persists or becomes painful despite your self-care efforts, medical treatments can provide relief:
- Trimming away excess skin. Your doctor can pare down thickened skin or trim a large corn with a scalpel, usually during an office visit. Don’t try this yourself because it could lead to an infection.
- Callus-removing medication. Your doctor may also apply a patch containing 40 percent salicylic acid (Callus Remover, Clear Away, others). Such patches are available without a prescription. Your doctor will let you know how often you need to replace this patch. He or she may recommend that you use a pumice stone, nail file or emery board to smooth away dead skin before applying a new patch. You can also get a prescription for salicylic acid in gel form to apply on larger areas.
- Medication to reduce infection risk. Your doctor may suggest applying an antibiotic ointment to reduce the risk of infection.
- Shoe inserts. If you have an underlying foot deformity, your doctor may prescribe custom-made padded shoe inserts (orthotics) to prevent recurring corns or calluses.
- Surgery. In rare instances, your doctor may recommend surgery to correct the alignment of a bone causing friction.