Inherent in walking or running is the battle between a fixed surface (the floor) and the foot delivering force with each step. Each step results in friction that can irritate the ball of the foot and the toes. In a response to friction, skin will often thicken to form a protective outer layer. We call this thickening a corn or callus.

Corns and calluses come in all shapes, sizes and varieties. Corns can be found on the tops of toes, between toes, at the tips of toes or even adjacent to the nail. A corn is simply the formation of a callus on a toe. The terms corn and callus can be used interchangeably, but for sake of conversation, a callus is a build up of skin on the bottom of the foot or heel, while a corn is a build up of callus on the toes. Initially, the formation of callus can be a helpful process. As the skin senses a mechanical irritation it responds by thickening, forming a callus. What do we mean by mechanical irritation? Well that could be a shoe that is too tight, it could be friction against the ground or it could even be the mechanical friction that occurs between two toes. In each case, corns form by the recurrent rub of mechanical friction.

The most common corn is due to contraction of the toe (hammer toe) placing pressure on the top of the toe from the toe box of the shoe. This type of corn, is referred to as a helloma dura (HD), or hard corn, and is often seen in cases of hammer toes where the toe is contracted and pushing against the roof of the shoe. Soft corns, on the other hand, are found between the toes. Soft corns, also known as HM's (helloma molle) or kissing corns, are commonly misdiagnosed as a chronic athlete's foot infection. With soft corns, we’ll see a breakdown of the skin between the toes. This breakdown is usually between the 4th and 5th toes.

Treatment of corns

The most important aspect of treating a corn is to be sure that the shoe is properly fit. Consider the formation of a hard corn to be no more complicated than the analogy of a square peg and a round hole. The foot is the square peg that just doesn't fit into the round hole (the shoe). Our choices are to make the round hole (shoe) bigger or softer by wearing a wider or softer shoe. Or we make the foot (square peg) more narrow by surgically correcting the foot. Alternatively a corn pad can also be used to cushion the corn. Common sense would tell us to first try to modify the shoe or use a corn pad.
The distal end of the shoe that covers the toes is called the toe box. The width and depth of the toe box are very important when trying to obtain a good fit. An improperly fit toe box can contribute to developing corns. Try this simple test. Stand barefoot on the floor. Place your shoe on the floor right next to your foot. Now compare the shape of your forefoot and the shape of the toe box. If the two are incompatible, you're looking for trouble and asking for a corn.

Corn pads and callus pads come in all kinds of shapes and sizes. Choosing the correct pad depends upon three things; (1) the location of the corn or callus (2) the type of shoe in which you intend to wear the pad and (3) the activity you plan to participate in while wearing the pad. Soft corns respond to the use of a pad that separates the toes. Soft corn pads can be made from silicone gel, soft foam or lambs wool. Many folks find relief with a simple cotton ball that’ll separate the toes. Foam and gel toes sleeves are another popular solution for hard corns. Hard corns can also be treated with gel cushions and adhesive backed felt ‘cut out’ pads.

Periodic paring (debridement) of a hard corn can help to reduce the thickness of the callus. This can be accomplished with a safety razor, callus file or pumice stone. Topical callus creams can also be used to soften callus prior to debridement.  Care should be exercised with medicated callus creams in patients with poor circulation or loss of sensation (peripheral neuropathy).

Permanent correction of corns can be accomplished by a number of different surgical procedures. The procedures vary dramatically based upon the type and location of the corn. Some corns are quite easy to correct, others a bit more difficult. Your podiatrist can help you determine whether you may be a candidate for surgical correction of your corn.

Well fitted shoes, a dose of prevention and a knowledge of treating corns can make a world of difference in your comfort.

Heloma dura - hard corn.
Heloma molle - soft corn.
HD - heloma dura or hard corn commonly found on the tops of toes.
HM - helloma molle, also known as a soft corn and found between the toes.
Interdigital corns - corns found between the toes.
Kissing corns - also known as an HM and found between the toes.
Lister's Corn - a corn found adjacent to the 5th toe nail. Very common on the outside of the little toe nail and appears to look like a second toe nail.
Soft corn - found between the toes. Most often between the 4th and 5th toes. Also called an HM

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The symptoms of corns can be mild to severe and includes pain that is described as a 'hot poker' to the toes.  Symptoms vary with location and severity.

A corn is a condition that can vary in both location and appearance. The differential diagnosis for this condition should include;

Abscess

Blister

Glomus tumor

Porokeratoma

Eccrine poroma

Infection

Malignant melanoma

Kaposi's Sarcoma

Psoriasis

Ulcer

Verrucae

Wart

• Cracked Heel

• Immersion Foot

• Toe Box Dermatitis

• Dry Skin

• Venous Stasis Dermatitis and Venous Ulcers

This article was written by Jeffrey A. Oster, DPM and last updated 4/27/10.

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