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| Callus | |
|---|---|
 | |
| Examples of callus found on the toe | |
| Specialty | Dermatology |
| Complications | Skin ulceration, infection |
Acallus (pl.:calluses) is an area of thickened and sometimes hardened skin that forms as a response to repeated friction, pressure, or other irritation. Since repeated contact is required, calluses are most often found on the feet and hands, but they may occur anywhere on the skin. Some degree of callus, such as on the bottom of the foot, is normal.[1]
Calluses are generally not harmful and help preventblisters, as well as offering protection.[2] However, excessive formation may sometimes lead to other problems, such as askin ulceration or infection, or cause the affected person to try to offload the affected painful area, which can place excessive stress on the asymptomatic side.
Rubbing that is too frequent or forceful will causeblisters, as opposed to calluses, to form.
Normally, a callus will form on any part of the skin exposed to excess friction over a long period of time. Activities that are known for causing calluses includeconstruction work and craftwork,the arts,[3]food preparation, manysports andphysical activities,[4][5] and fashion choices like wearinghigh heels.[6]
Although calluses can occur anywhere on the body as a reaction to moderate, constant "grinding" pressure, they are most often found on thefoot (where the most pressure and friction are applied). On the feet (arguably the source of the most problematic calluses), they typically form on the metatarsal-phalangeal joint area ("balls of the foot"), heels and small toes due to the compression applied by tightly fitting shoes.
Biologically, calluses are formed by the accumulation ofterminally differentiatedkeratinocytes in the outermost layer of skin. Though the cells of calluses are dead, they are quite resistant to mechanical and chemical damage due to extensive networks of cross-linked proteins andhydrophobic keratinintermediate filaments containing manydisulfide bonds.[7] It is the natural reaction of thepalmar orplantar skin. Too much friction occurring too fast for the skin to develop a protective callus will cause ablister orabrasion instead.
Sometimes a callus occurs where there is no rubbing or pressure. Thesehyperkeratoses can have a variety of causes. Some toxic materials, such asarsenic, can cause thick palms and soles. Some diseases, such assyphilis, can cause thickening of the palms and soles as well as pinpoint hyperkeratoses. There is a benign condition calledkeratosis palmaris et plantaris, which produces corns in the creases of the fingers and non-weight bearing spaces of the feet. Some of this may be caused byactinic keratosis, which occurs due to overexposure to sun or with age and hormonal shifts.
Acorn (orclavus, pluralclavi) is a cone-shaped callus that penetrates into the dermis, usually on the feet or hands. Corns may form due to chronic pressure or rubbing at a pressure point (the skin over a bone), or due to scar tissue from a healing wound creating pressure in a weight-bearing area such as the sole of the foot. If there is constant stimulation of the tissue producing the corns, even after the corn is surgically removed, the skin may continue to grow as a corn.[1]
The hard part at the center of the corn resembles a funnel with a broad raised top and a pointed bottom. Because of their shape, corns intensify the pressure at the tip and can cause deep tissue damage andulceration.[8] The scientific name for a corn isheloma (pluralhelomata). A hard corn is called aheloma durum, while a soft corn is called aheloma molle.
The location of the soft corns tends to differ from that of hard corns. Hard corns occur on dry, flat surfaces of skin. Soft corns (frequently found between adjacent toes) stay moist, keeping the surrounding skin soft. The corn's center is not soft however, butindurated.
The specific diagnostic workup and treatments for corns may differ substantially from other forms of calluses.
Corns and calluses are easier to prevent than to treat. When it is undesirable to form a callus, minimizing rubbing and pressure will prevent callus formation. Footwear should be properly fitted,[9] gloves may be worn, and protective pads, rings or skin dressings may be used. People with poor circulation or sensation should check their skin often for signs of rubbing and irritation so they can minimize any damage.[citation needed]
Calluses and corns may heal by themselves eventually, once the irritation is consistently avoided. They may also be dissolved withkeratolytic agents containingsalicylic acid, sanded down with apumice stone orsilicon carbidesandpaper or filed down with acallus shaver, orpared down by a professional such as apodiatrist.[10]
People withdiabetes face special skin challenges. Because diabetes affects thecapillaries, the small blood vessels which feed the skin, thickening of the skin with callus increases the difficulty of supplying nutrients to the skin.[11] Callus formation is seen in high numbers of patients with diabetes, and together with absent foot pulses and formation ofhammer toe,[12][13] this may be an early sign of individuals at an increased risk for foot ulcers.[12]
The stiffness of a callus or corn, coupled with the shear and pressure that caused it, may tear the capillaries or adjoining tissue, causing bleeding within the callus or corn. This can often be result of trying to pick, cut, or shave off the callus by yourself at home. Although the bleeding can be small, sometimes small pools of blood orhematoma are formed. The blood itself is an irritant, a foreign body within the callus that makes the area burn or itch. If the pool of blood is exposed to the outside, infection may follow. Infection may also lead toulceration. This process can be prevented at several places. Diabetic foot infections are the leading cause of diabetic limbamputation.
Calluses in the hands are frequently associated withmanual labor andblue-collar workers.[14][15][16] During theGads Hill Train Robbery in 1874, theJames–Younger Gang purportedly refrained from robbing men with calloused hands, assuming them to be working class laborers.[17][18] A similar notion is also present inMāori culture, where the wordsraupā andraupo refer to hands left cracked and chapped due to manual work, and are used assimiles for someone deemed a hard worker.[19][20]
Calluses have also been known to develop on the forehead from the frequent prostrations required inMuslim prayer; known as aprayer bump orzebiba, such calluses are considered marks of piety in some Muslim countries, and people have been known to take special steps, such as praying on straw mats, to encourage the callus to develop.[21]
Calluses may also form on thefingertips from the repeated pressure and friction of playing stringed instruments. This formation of calluses allows the player to repeatedly depress the strings without causing pain. Because of this, callus formation is viewed as something of a rite of passage for beginner string players.
Calluses also commonly form on the palms of the hands in certain athletic sports such asweightlifting andgymnastics due to the repeated gripping of bars.
You should not have to "break in" shoes if they fit properly.