callus

{{Infobox medical condition (new)

| name = Callus

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| image = Evolucion de un callo.jpg

| caption = Examples of callus found on the toe

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| field = Dermatology

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| complications = Skin ulceration, infection

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File:Calluses.jpg

A callus ({{plural form}}: 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.

Calluses are generally not harmful and help prevent blisters, as well as offering protection.[https://footwearnews.com/2019/focus/health/are-calluses-bad-for-feet-cracked-heels-1202801034/ Are Calluses Actually Bad for Your Feet? See What Podiatrists Have to Say], Footwear News However, excessive formation may sometimes lead to other problems, such as a skin 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 cause blisters, as opposed to calluses, to form.

Cause

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 include construction work and craftwork, the arts,{{Cite journal |last1=Sims |first1=Susan E. G. |last2=Engel |first2=Laura |last3=Hammert |first3=Warren C. |last4=Elfar |first4=John C. |date=2015-08-05 |title=Hand Sensibility, Strength, and Laxity of High-Level Musicians Compared to Non- Musicians |journal=The Journal of Hand Surgery |volume=40 |issue=10 |pages= 1996–2002.e5|doi=10.1016/j.jhsa.2015.06.009 |issn=0363-5023 |pmc=4584184 |pmid=26253604}} food preparation, many sports and physical activities,{{Cite journal |last1=Grima |first1=Joseph N. |last2=Vella Wood |first2=Michelle |last3=Portelli |first3=Nadia |last4=Grima-Cornish |first4=James N. |last5=Attard |first5=Daphne |last6=Gatt |first6=Alfred |last7=Formosa |first7=Cynthia |last8=Cerasola |first8=Dario |date=2022-01-05 |title=Blisters and Calluses from Rowing: Prevalence, Perceptions and Pain Tolerance |journal=Medicina |volume=58 |issue=1 |pages=77 |doi=10.3390/medicina58010077 |issn=1010-660X |pmc=8779584 |pmid=35056385|doi-access=free }}{{Cite journal |last1=Emer |first1=Jason |last2=Sivek |first2=Rachel |last3=Marciniak |first3=Brian |date=2015-04-08 |title=Sports Dermatology: Part 1 of 2 Traumatic or Mechanical Injuries, Inflammatory Conditions, and Exacerbations of Pre-existing Conditions |journal=The Journal of Clinical and Aesthetic Dermatology |volume=8 |issue=4 |pages= 31–43|issn=1941-2789 |pmc=4456799 |pmid=26060516}} and fashion choices like wearing high heels.{{Cite web |last=Bouchez |first=Colette |date=2009-02-09 |editor-last=Chang |editor-first=Louise |title=Tips to Avoid Foot Pain From High Heels |url=https://www.webmd.com/women/features/tips-to-avoid-foot-pain-from-high-heels |access-date=2022-03-10 |website=WebMD |language=en}}

Although calluses can occur anywhere on the body as a reaction to moderate, constant "grinding" pressure, they are most often found on the foot (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 of terminally differentiated keratinocytes 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 and hydrophobic keratin intermediate filaments containing many disulfide bonds.{{cite journal |vauthors=Tantisiriwat N, Janchai S |title=Transglutaminases: multifunctional cross-linking enzymes that stabilize tissues. |journal=The FASEB Journal |volume=5 |issue=15 |pages=3071–7 |date=Dec 1991 |doi=10.1096/fasebj.5.15.1683845 |pmid=1683845 |s2cid=6751428 |url=http://www.fasebj.org/content/5/15/3071.long|doi-access=free |url-access=subscription }} It is the natural reaction of the palmar or plantar skin. Too much friction occurring too fast for the skin to develop a protective callus will cause a blister or abrasion instead.

Sometimes a callus occurs where there is no rubbing or pressure. These hyperkeratoses can have a variety of causes. Some toxic materials, such as arsenic, can cause thick palms and soles. Some diseases, such as syphilis, can cause thickening of the palms and soles as well as pinpoint hyperkeratoses. There is a benign condition called keratosis 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 by actinic keratosis, which occurs due to overexposure to sun or with age and hormonal shifts.

=Corns=

Image:Corns.jpg

A corn (or clavus, plural clavi) 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 (in this 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.{{Cite web |title=Corns and Calluses: Symptoms, Treatment & Care Tips |url=https://my.clevelandclinic.org/health/diseases/16896-corns-and-calluses |access-date=2022-03-10 |website=Cleveland Clinic}}

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 and ulceration.{{Cite journal |last=Silverberg |first=Nanette B. |date=2019 |title=Corns (Clavus): Background, Pathophysiology, Etiology |url=https://emedicine.medscape.com/article/1089807-overview |journal=Medscape |url-access=registration}} The scientific name for a corn is heloma (plural helomata). A hard corn is called a heloma durum, while a soft corn is called a heloma 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, but indurated.

The specific diagnostic workup and treatments for corns may differ substantially from other forms of calluses.

Prevention

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,{{cite web | url = http://www.webmd.com/a-to-z-guides/finding-the-right-footwear-for-your-foot-problem | title = Foot problems: Finding the right shoes | first = Shannon | last = Erstad | date = 6 March 2008 | work = WebMD Medical Reference from Healthwise | publisher = Healthwise | at = How do I find the right shoes? | access-date = 2010-06-10 | quote = You should not have to "break in" shoes if they fit properly.}} 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.{{cn|date=August 2022}}

Treatment

File:Callus patient 17th century.jpgs, 17th century]]

Calluses and corns may heal by themselves eventually, once the irritation is consistently avoided. They may also be dissolved with keratolytic agents containing salicylic acid, sanded down with a pumice stone or silicon carbide sandpaper or filed down with a callus shaver, or pared down by a professional such as a podiatrist.[http://www.mayoclinic.com/health/corns-and-calluses/DS00033/DSECTION=treatments-and-drugs Corns and calluses: Treatments and drugs]. Mayo Clinic. Retrieved July 23, 2009.

=Diabetes=

People with diabetes face special skin challenges. Because diabetes affects the capillaries, the small blood vessels which feed the skin, thickening of the skin with callus increases the difficulty of supplying nutrients to the skin.{{Cite journal |last1=Boulton |first1=Andrew J. |last2=Meneses |first2=Patricio |last3=Ennis |first3=William J. |date=January–February 1999 |title=Diabetic foot ulcers: A framework for prevention and care |url=https://institutobeatrizyamada.com.br/wp/wp-content/uploads/artigos-iby/Diabetic-foot-ulcers-A-framework-for-prevention-and-care.pdf |journal=Wound Repair and Regeneration |volume=7 |issue=1 |pages=9–10|doi=10.1046/j.1524-475x.1999.00007.x |pmid=10231501 |s2cid=37720400 }} Callus formation is seen in high numbers of patients with diabetes, and together with absent foot pulses and formation of hammer toe,{{cite journal |vauthors=Alavi A, Sanjari M, Haghdoost A, Sibbald RG |title=Common foot examination features of 247 Iranian patients with diabetes |journal=International Wound Journal |volume=6 |issue=2 |pages=117–22 |date=April 2009 |pmid=19432661 |doi=10.1111/j.1742-481X.2009.00583.x |pmc=7951794 }} -12% having callus formation{{cite journal |vauthors=Tantisiriwat N, Janchai S |title=Common foot problems in diabetic foot clinic |journal=J Med Assoc Thai |volume=91 |issue=7 |pages=1097–101 |date=July 2008 |pmid=18839852 }} -56% having callus present this may be an early sign of individuals at an increased risk for foot ulcers.

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 or hematoma 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 to ulceration. This process can be prevented at several places. Diabetic foot infections are the leading cause of diabetic limb amputation.

Society and culture

Calluses in the hands are frequently associated with manual labor and blue-collar workers.{{Cite book |last=Hoelle |first=Jeffrey |url=https://books.google.com/books?id=qMAvBgAAQBAJ |title=Rainforest Cowboys: The Rise of Ranching and Cattle Culture in Western Amazonia |date=2015-04-15 |publisher=University of Texas Press |isbn=978-0-292-76134-6 |pages=66, 74, 82, 179 |language=en}}{{Cite journal |last=Gradenwitz |first=Alfred |date=1907-12-28 |title=The Influence of Profession on the Shape of the Hand |url=https://zenodo.org/record/1864135 |journal=Scientific American |volume=97 |issue=26 |pages=478|doi=10.1038/scientificamerican12281907-478 }}{{Cite web |last=Fiouzi |first=Andrew |date=2019-10-25 |title=Why We Fetishize Working-Class Hands |url=https://melmagazine.com/en-us/story/why-we-fetishize-working-class-hands |access-date=2022-03-10 |website=MEL Magazine |language=en-US}} During the Gads Hill Train Robbery in 1874, the James–Younger Gang purportedly refrained from robbing men with calloused hands, assuming them to be working class laborers.{{Cite web |last=Nickell |first=Frank |date=2021-09-07 |title=Almost Yesterday: The Gads Hill Train Robbery |url=https://www.krcu.org/education/2021-09-07/almost-yesterday-the-gads-hill-train-robbery |access-date=2022-03-10 |website=KRCU Public Radio |language=en}}{{Cite book |last=Wukovits |first=John F. |url=https://books.google.com/books?id=GFScUxOKOtMC |title=Jesse James |publisher=Chelsea House Publishers |year=1997 |isbn=978-0-7910-3876-5 |pages=32 |language=en |author-link=John F. Wukovits}} A similar notion is also present in Māori culture, where the words raupā and raupo refer to hands left cracked and chapped due to manual work, and are used as similes for someone deemed a hard worker.{{Cite book |last=Black |first=Hona |url=https://books.google.com/books?id=km0vEAAAQBAJ |title=He Iti te Kupu: Māori Metaphors and Similes |date=2021-05-01 |publisher=Oratia Media Ltd |isbn=978-0-947506-91-9 |language=en}}{{Cite web |title=Maori Proverbs with their English Translation - Whakatauki |url=https://www.maori.cl/Proverbs.htm |access-date=2022-03-10 |website=www.maori.cl}}

Calluses have also been known to develop on the forehead from the frequent prostrations required in Muslim prayer; known as a prayer bump or zebiba, 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.{{cite web |last=Slackman |first=Michael |date=December 18, 2007 |title=Fashion and Faith Meet, on Foreheads of the Pious |url=https://www.nytimes.com/2007/12/18/world/africa/18egypt.html |access-date=2018-08-08 |website=New York Times}}

Calluses may also form on the fingertips 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 as weightlifting and gymnastics due to the repeated gripping of bars.