A callouse (or callus) is a toughened tissue on the surface of the skin, which has developed due to constant pressure, friction and irritation on the area. Calluses can be frequently developed on the feet due to constant pressure due to walking. It can also occur on the hands because of similar mechanism like holding a pen in a specific position repeatedly. Calluses are not harmful and may not be asymptomatic; however, some may lead to mild pain, infection and ulceration.
Usually, callouses form on a specific are in the skin that is exposed to constant pressure. Because of constant pressure in the area, the keratinocytes proliferate to protect the area from injury. As a result, there is thickening of the outermost portion of the skin. The cells in the callouses are usually dead, but they still are able to protect the area from constant friction and pressure due to a cross-link of proteins and many disulfide bonds in the area, making it resistant to chemical and physical insults.
The most common locations of callouses on the hands are in the middle finger, where a pen constantly put pressure on the area; the four left fingers due to constantly holding the strings down among guitar and violin players and ion the right hand fingers due to strumming, slapping and use of pizzicato. Motorcycle and bicycle riders may also develop callouses on the palms near the junction of the fingers due to constant pressure on the hand grips. Aside from the hands, the foot is the most common site of callouses because it bears the weight in the body that further increases the pressure. Wearing ill-fitting shoes, high heels with narrow toe area and certain toe malformations may result in foot callouses. Other causes of callous in the hands and feet may include martial arts, dancing (especially ballet), weight training, praying, digging, racket sports, rowing and chopping wood. Bowlers may also develop calluses on the thumb.
Callouses usually develop over a prolonged period of friction in contrast to abrasion and blisters, which develop after too much friction in a significantly short duration.
In contrast to the callouses that develop with pressure, certain callouses may also develop even without pressure or friction. This may be due to arsenic poisoning, which leads to thickening of the soles and palms. Syphilis may also cause hyperkeratosis of the palms. Actinic keratosis, an increased keratinocyte build-up may also lead to callouses on sun exposed areas. Keratosis palmaris et planatris also produces corns and callouses on the non-weight bearing spaces on the feet as well as in the creases of the fingers.
Callouses are usually easy to remove, but some may require specialized treatment. Softening the callous by soaking the feet in lukewarm water and rubbing it with pumice stone afterwards is usually effective, but large callouses may need repeated treatments. You can also apply aloe cream, petroleum jelly and lanolin in order to soften the area for easier removal.
Find out more about this and other conditions by visiting Dr. Mohr, your Wesley Chapel chiropractor.