What Are Corns And Calluses? What Causes Corns And Calluses?

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Main Category: Dermatology
Article Date: 30 Nov 2009 - 5:00 PST

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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.

According to Medilexicon's medical dictionary:

Callosity is "A circumscribed thickening of the keratin layer of the epidermis as a result of repeated friction or intermittent pressure."

A corn is "A hard or soft hyperkeratosis of the sole of the human foot secondary to friction and pressure."

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.

Although complications are uncommon, people with diabetes or other conditions which affect circulation to their feet are more susceptible.

What are the signs and symptoms of corns and calluses?

A symptom is something the patient feels and reports, while a sign is something other people, such as the doctor detect. For example, pain may be a symptom while a rash may be a sign.

Patients often say they feel as if they are walking on stones. The following signs or symptoms may indicate the presence of corns or calluses:

• A raised bump which is hardened
• A thick and rough area of skin
• Flaky and dry skin
• Flaky and waxy skin
• Pain under the skin
• Tenderness under the skin

People sometimes mistakenly use the terms corns and calluses interchangeably - but they are not the same:

Corns versus calluses

• Corns are smaller than calluses
• Corns generally (not always) have a hard center
• Corns have a hard center surrounded by inflamed skin
• Corns usually occur in non-weight bearing parts of skin (not always)
• Corns can be painful when pressed
• Calluses are not generally painful
• Calluses are usually larger than corns, and vary in shape
• Calluses generally develop on the soles of the feet, especially under the heels or balls, on the palms of the hands, and also on the knees.

If a corn or callus becomes very inflamed or painful the sufferer should seek medical advice. Patients with poor circulation, such as those with diabetes, should talk to their doctors before self treating corns and calluses.

What are the risk factors for corns and calluses?

A risk factor is something which increases the likelihood of developing a condition or disease. For example, obesity significantly raises the risk of developing diabetes type 2. Therefore, obesity is a risk factor for diabetes type 2. The following risk factors are linked to a higher incidence of corns and calluses:

• Bunions, hammertoe and other foot problems and deformities - a bunion is an abnormal, bony bump that develops on the joint at the base of the big toe. A hammertoe is when a toe becomes curled up like a claw.
  
  
• Excessive hand friction - people who use hand tools without wearing gloves have a higher risk of developing calluses.
  
  
• Old age - elderly people have less fatty tissue in their skin, which can result in less padding and a higher risk of developing calluses, especially on the ball of their foot.

What are the causes of corns and calluses?

Anything that results in higher levels of pressure or friction on the skin can cause corns or calluses to develop.

• Badly fitting shoes - the shoes may be too tight (pressure), or sometimes too loose (rubbing/friction). Very high heels. A badly placed seam in a shoe can rub against the skin.
  
  
• Socks - either not wearing any socks or having socks that don't fit properly.
  
  
• Hand tools - some work, house or garden tools, if used repetitively, can cause calluses in the person's hands.
  
  
• Walking barefoot - if done regularly, the skin will thicken to protect itself.
  
  
• Repeated actions on the feet (or one foot) - jogging or walking in an odd way.

Diagnosis of corns and calluses

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.

If the doctor suspects there may be an underlying bone structure problem the patient may be referred for an X-ray.

What are the treatment options for corns and calluses?

If the corns and calluses have been caused by repetitive actions, avoiding them will most probably solve the problem. Wearing shoes and socks that fit properly, as well as having protective pads and other self-care measure also help.

If the corn or callus does not go away, or continues to be painful regardless, the following therapies may help:

• Creams - special creams may be recommended to rehydrate areas with extra thick skin.
  
  
• Trimming or removing - the doctor pares down the thickened skin, or uses a scalper to trim a large corn. A podiatrist (foot doctor) may remove some of the hard skin that surrounds the corn so that the center of it can be removed.
  
  
• Salicylic acid - after trimming the doctor may apply a patch with 40% salicylic acid. The patient will need to replace the patch periodically. A pumice stone or metal nail file is usually used to rub away dead skin before applying a new patch.
  
  
• Foam wedges - these may be used for corns on the toes to reduce pressure. Sometimes special silicone wedges may be used.
  
  
• Antibiotics - an antibiotic ointment may be prescribed to lessen the risk of infection.
  
  
• Orthotics - these are custom-made padded shoe inserts which may help people with an underlying foot deformity.
  
  
• Bone problem surgery - the bone may need to be surgically aligned (rare).

How to prevent corns and calluses?

The following measures may help reduce the risk of developing corns and calluses:

• Wash your feet with soap and water every evening. Use a scrubbing brush.
  
  
• Apply a specially moisturizing foot cream after washing and drying them well. Do not use a body lotion.
  
  
• Make sure your shoes and socks are well-fitting, and with seams that do not rub the skin.
  
  
• Buy your shoes later on during the day - i.e. when trying on new shoes do so when your feet are at their largest (feet swell slightly as the day progresses).
  
  
• Any foot pain or skin irritation in the foot should not be ignored.
  
  
• Regularly see a foot specialist for a foot checkup.
  
  
• When trimming your toenails, cut straight across, and not down at angles or over the edges.
  
  
• Use a pumice stone or foot file regularly. Make sure you remove hard skin gently.
  
  
• Change your socks every day. Do not let your feet become sweaty.
  
  
• Protect your hands - when using tools, either wear padded gloves or pad the tool handles.

Written by Christian Nordqvist
Copyright: Medical News Today
Not to be reproduced without permission of Medical News Today