Corns (Clavus)

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Background

A corn (also termed clavus) is a thickening of the skin due to intermittent pressure and frictional forces. These forces result in hyperkeratosis, clinically and histologically. The extensive thickening of the skin in a corn may result in chronic pain, particularly in the forefoot; in certain situations, this thickening may result in ulcer formation. The word clavus has many synonyms and innumerable vernacular terms, some of which are listed in the Table below; these terms describe the related activities that have induced clavus formation.

Synonyms for clavus include callosity, a hyperkeratotic response to trauma; corn, heloma, or a circumscribed hyperkeratotic lesion that may be hard (ie, heloma durum) or soft (ie, heloma molle); and callous, callus, or a diffusely hyperkeratotic lesion. Localized callosities of the soles, which do not resolve, are termed plantar callus, heloma, tyloma, keratoma, or plantar corn. When callosities occur over one or more lateral metatarsals, they are termed intractable plantar keratoses.[1]

Corns are often seen in athletes and in patient populations exposed to uneven friction from footwear or gait abnormalities, including elderly persons, diabetic patients, and amputees.[2] Abnormal foot mechanics, foot deformities, high activity level, and more serious conditions such as peripheral neuropathy also contribute to the formation of corns.[3] Corns are associated with considerable morbidity secondary to pain; fortunately, many treatment and preventative options are available that provide a high rate of mitigation.[4]

Clinically, all these lesions look like hyperkeratotic or thickened skin. Maceration and secondary fungal or bacterial infections are a common overlying feature in heloma molle and diabetes. Plantar helomas tend to have a central keratin plug, which, when pared, reveals a clear, firm, central core. The most common sites for clavus formation are the feet, specifically the dorsolateral aspect of the fifth toe for heloma durum, in the fourth interdigital web of the foot for heloma molle, and under the metatarsal heads for calluses. Clinically, three types of corns have been described. The first is a hard corn, or heloma durum, notable for its dry, horny appearance. It is found most commonly over the interphalangeal joints. The second is a soft corn, or heloma molle, described as such because of its macerated texture secondary to moisture. It is generally found in interdigital locations.[5, 6] The third type is a periungual corn, and this type occurs near or on the edge of a nail.[7] Note the image below.



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Hard corn over the proximal interphalangeal joint of second toe. Courtesy of James K. DeOrio, MD.

Corns are often misdiagnosed as calluses, which are also hyperkeratotic skin lesions resulting from excess friction. However, calluses develop from forces distributed over a broad area of skin, whereas corns develop from more localized forces.[8] Calluses are often considered desirable for some activities (eg, gymnastics, weightlifting), and they lack a central core, which is characteristically revealed in corns upon removal of the upper hyperkeratotic layer of skin. Corns can occur within an area of callus,[9] such as on the plantar surface. Note the image below.



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Calluses on the palmar surface of the hands of a body builder. Courtesy of James K. DeOrio, MD.

Table. Clavus Formation Named for Specific Etiology or Location



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See Table

A clinical image of a screwdriver operator's clavus is below.



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Screwdriver operator's callus (ie, clavus).

Pathophysiology

Corns are the result of mechanical trauma to the skin culminating in hyperplasia of the epidermis. Most commonly, friction and pressure between the bones of the foot and ill-fitting footwear cause a normal physiological response—proliferation of the stratum corneum. One of the primary roles of the stratum corneum is to provide a barrier to mechanical injury. Any insult compromising this barrier causes homeostatic changes and the release of cytokines into the epidermis, stimulating an increase in synthesis of the stratum corneum. When the insult is chronic and the mechanical defect is not repaired, hyperplasia and inflammation are common.[26] With corns, external mechanical forces are focused on a localized area of the skin, ultimately leading to impaction of the stratum corneum and the formation of a hard keratin plug that presses painfully into the papillary dermis, which is known as a radix or nucleus.[6, 8]

The shape of the hands and feet are important in corn (clavus) formation. Specifically, the bony prominences of the metacarpophalangeal and metatarsophalangeal joints often are shaped in such a way as to induce overlying skin friction. As corn formation ensues, friction against the footwear is likely to perpetuate hyperkeratosis. Repetitive motion can produce callosities, as would be seen in musicians.[22]

Toe deformity, including contractures and claw, hammer, and mallet-shaped toes, may contribute to pathogenesis. Deformity of the feet from underlying conditions such as rheumatoid arthritis can contribute to clavus formation.[23] Bunionettes, ie, callosities over the lateral fifth metatarsal head, may be associated with neuritic symptoms due to compression of the underlying lateral digital nerves. Furthermore, Morton toe, in which the second toe is longer than the first toe, occurs in 25% of the population; this may be one of the most important pathogenic factors in a callus of the common second metatarsal head, ie, an intractable plantar keratosis.

Long-term or repetitive motion may also induce clavus formation, as is seen in computer users and text messengers (ie, "mousing" callus).[24] Callosities can also form from excessive leg crossing.[25]

Etiology

Both hard and soft corns are caused by pressure from unyielding structures.[5] Abnormal mechanical stress may be intrinsic or extrinsic. Intrinsic factors include foot deformities (eg, hammer toe, bunion)[27] ; abnormal foot mechanics (acquired or hereditary); and peripheral neuropathy. Extrinsic factors include poorly fitting footwear and heavy activity (athletics).

A 2005 study conducted by Menz et al reported that in older populations, plantar pressures are significantly higher under callused regions of the foot.[28] These data support the idea that increased pressures are related to a hyperkeratotic response and that the target for treatment should be eliminating excess pressures on the foot.

Conditions associated with clavus formation include the following:

Faulty mechanics play a role. Irregular distribution of pressure and repetitive motion injury (especially in athletes) are believed to be the main inciting causes; however, inappropriately shaped or constrictive footwear in the presence of bony prominences (eg, talar bone prominences[35] ) may exacerbate corn formation. Furthermore, some disorders may alter the shape or sensation of the soles of the feet. Bony prominences and faulty foot mechanics then allow clavus formation to continue.[36, 37, 38, 39, 40]

Epidemiology

Frequency

United States

Corns are one of the most common foot conditions in the United States, particularly amongst older patients. It is a common disorder because of the frequency of usage of occlusive footwear and participation in repetitive activities, such as running.

International

Corns are common worldwide. Any weight-bearing human is susceptible to the development of corns.

Race

An epidemiological study evaluating the prevalence of foot conditions amongst a diverse sample of adults from the northeastern United States revealed a significant difference in rates of corns amongst ethnic groups. African Americans had a significantly higher rate of corns and calluses compared with non-Hispanic white and Puerto Rican participants (70% vs 58% vs 34.1%).[43]

Sex

Amongst elderly populations, both men and women have been reported to wear shoes too narrow for their feet. Women have been reported to wear shoes that are also shorter than their feet. Both narrow and short footwear can lead to the development of corns, in addition to foot deformities.[44] They are more common in women than in men because of this use of occlusive and poorly fitted footwear.

Age

Hyperkeratotic lesions of the foot (including corns and calluses) have been reported to affect 20-65% of people aged 65 or older.[43, 45, 46]  

Anyone can have a clavus, but most individuals acquire the risk factors for clavus formation after puberty because of the onset of traumatic footwear use, repetitive motion injuries, and progressive foot deformities.

Prognosis

Recurrence is common. The most common symptoms associated with corns are pain upon ambulation and restriction of activity secondary to pain. Corns are generally not associated with mortality; however, recognizing the potential for a maltreated corn, soft corns in particular, to develop into a life-threatening secondary infection (bacterial or fungal) is important in patients with diabetes mellitus or immunosuppression.

The prognosis depends on the underlying cause of the callous formation and whether interventions can successfully be introduced to eliminate the repetitive motion. Chronic clavus generally occurs because of the difficulty in removing inciting factors in most situations. Extensive thickening of the skin may result in chronic pain, particularly in the forefoot; in certain situations, ulcer formation may result. Clavus may be a sign of underlying neuropathy due to diabetes or neuroborreliosis, or owing to the deformities of rheumatoid arthritis. In the case of neuropathy, a clavus may hide ulceration or denote abnormal neurovasculature of the feet. In the case of rheumatoid arthritis, corns may enhance the pain of deformed joints.

See Type 1 Diabetes Mellitus, Type 2 Diabetes Mellitus, and Diabetic Foot Infections for follow-up information.

Patient Education

Patients must be taught to wear less traumatic footwear, such as shoes with a wide toe space. Using inner soles, lowering the heel (if second metatarsal head lesions are present), and preventing the repetitive injuries that cause occupational clavus formation may be helpful. Review of proper footwear and trauma reduction may reduce disease severity over time.

For patient education resources, see the patient education article Corns and Calluses.

History

Commonly, a patient reports the development of a localized growth on their foot or toes that causes pain with ambulation or when wearing shoes.[4, 7]

A clavus forms because of inappropriate distribution of pressure onto a specific site, usually of the foot. A localized callosity of the soles, which does not resolve, is termed plantar callus, heloma, tyloma, keratoma, or plantar corn. When callosities occur over one or more lateral metatarsals, they are termed intractable plantar keratoses.

Physical Examination

Clinically, all variants of clavus lesions look like hyperkeratotic or thick skin; maceration and secondary fungal or bacterial infections are a common overlying feature in heloma molle and diabetes. Plantar helomas tend to have a central keratin plug, which, when pared, reveals a clear, firm, central core. The most common sites for clavus formation are the feet, specifically the dorsolateral aspect of the fifth toe for heloma durum, in the fourth interdigital web of the foot for heloma molle, and under the metatarsal heads for calluses.

Corns are typically located between toe clefts, on the plantar aspect beneath prominent metatarsals, or on the dorsal aspect of toe joints.[8] The patient’s gait should be observed to identify irregular mechanics.[6] Additionally, surrounding erythema and heat may be present if the corn is acutely irritated.[5] Multiple physical signs, as follows, can be evaluated in order to differentiate between a clavus, callus, and wart:

A hard corn is a firm, dry, and tender lesion with a shiny polished surface. If the upper layers are pared, a small, 1- to 2-mm translucent central core may be seen within the base of the lesion. Hard corns usually occur on the dorsolateral aspect of the fifth toe.[5] A plantar corn is a type of hard corn most commonly associated with a central core. These corns are located beneath the metatarsal heads of the toes.[5] Plantar corns that do not respond to conservative medical treatment are referred to as intractable plantar keratosis.[48] Note the image below.



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Hard corn on the lateral surface of fifth toe. Courtesy of James K. DeOrio, MD.

A soft corn is boggy and macerated so that it appears white. Soft corns usually occur in the fourth interdigital space.[5]

Examination of patients should include assessment of the types of footwear worn, activities performed, gait, and current home therapy or previously prescribed therapy.

Lesions should be palpated and pared to look for underlying blood vessels (black dots or pinpoint bleeding), which are seen in warts, and to look for underlying ulcerations, as seen in neurovascular ulcerations (especially in patients with diabetes).

Paring of callosities or corns, as opposed to plantar warts, should reveal normal dermatoglyphics.[49]

Callosities are generally more painful with direct pressure, whereas warts are more painful with lateral pressure.[50]

Pedobarographic studies are pressure assessments that may be used to detect an altered distribution of foot pressure. MRI may delineate diabetic foot problems more clearly.

Biopsy of lesions reveals hyperkeratosis and, occasionally, mucin deposition.

Complications

Complications include secondary bacterial or fungal infection in patients with diabetes or in patients with immunosuppression. With deep paring, be aware of the risk of bleeding and infection.[7]

Corns are often in close proximity to joints and bones, increasing the chances for septic arthritis or osteomyelitis to occur if left untreated.

Patients, particularly patients with diabetes, may have ulcerations from chronic pressure. This can lead to infection and cellulitis.

Maceration and tinea pedis also may occur.

Laboratory Studies

No routine laboratory tests are necessary to evaluate a patient with corns (clavus).[6] Diabetes mellitus, tertiary lues, and other causes of neuropathy should be excluded.

Blood glucose testing is required when paring of a clavus reveals an ulcer or when diabetes mellitus is suspected. In the setting of neuropathy, neuroborreliosis should be considered, and testing is performed with Lyme titers. Rheumatoid factor testing for deformities consistent with rheumatoid arthritis may be indicated. Also see Lyme Disease and Rheumatoid Arthritis.

Imaging Studies

Imaging studies are required in clavus patients only to detect underlying bony abnormalities. Studies may include radiography and, occasionally, CT scanning of the affected area with bone window settings.[51] Radiographs of the feet in a weight-bearing position are useful for identifying bony prominences and the presence of underlying pathology contributing to foot pain.[34] However, a physical examination may be sufficient to evaluate smaller toe abnormalities.[34]

Other Tests

Pedobarographic studies are pressure assessments that may be used in clavus patients to detect an altered distribution of foot pressure.

Procedures

Dermoscopic examination before and after trimming can be helpful with the differential diagnosis of plantar warts, corns, calluses, and healed warts. The translucent central core known as a nucleus may be visualized more easily in a corn using dermoscopy.[49]

Biopsy of the lesions reveals hyperkeratosis and, occasionally, mucin deposition. Paring of the corn can relieve pressure temporarily. Biopsy may be helpful in considering some of the other differential diagnoses, such as warts. Additionally, biopsy can be performed to differentiate clavus from porokeratosis palmoplantaris et disseminatum or discreta. These disorders occur in those aged 20-40 years who have hyperkeratotic plaques on the palms and soles. Biopsy shows a cornoid lamella.

Histologic Findings

Corns demonstrate epidermal hyperplasia with a thick and compact stratum corneum. Whereas calluses demonstrate only orthokeratosis, parakeratosis may be present in corns, and biopsy specimens demonstrate an endophytic cup shape. The granular cell layer may be decreased or absent.[8, 9] The dermis may occasionally show fibrosis with hypertrophied nerves and scar tissue replacing subcutaneous fat.[8]

Medical Care

When treating hard corns (clavi), the primary objective is to debulk or pare the lesion without drawing blood. Treatment should be aimed at reducing symptoms such as pain and discomfort with walking. Paring of the lesions immediately reduces pain. Following preparation of the skin with alcohol or iodine, a No. 15 surgical blade can be used with or without anesthesia to gradually remove sequential layers of keratin.[6] Once the etiology of the foot pressure irregularity is determined, attempts at pressure redistribution should be made. The final treatment goals are to remove the central keratin core for short-term pain relief and to reshape the skin to provide long-term prevention of excess friction.[7, 8] Regular debridement in high-risk populations, such as diabetic patients, may decrease the incidence of ulceration and, consequently, the need for surgical intervention.[52]

The use of orthotics and conservative footwear with extra toe space are often beneficial. When all else fails, surgery may be performed.

If abnormal dermatoglyphics or pinpoint bleeding is seen, wart therapy is initiated. If normal dermatoglyphics are noted, salicylic acid compounds and orthotics may be beneficial. Relief of symptoms may be achieved by thinning and cushioning of the involved lesions.

Paring of the lesions immediately relieves pain, especially with helomas. Lesions may be maintained in this state if the patient uses short soaks and pumice stone debridement at home. Debridement may be enhanced with the use of keratolytic agents, such as ureas, alpha-hydroxy acid (eg, glycolic, malic, or lactic acid), or beta-hydroxy acid (eg, salicylic acid).[53] Garlic extracts have also been described as being helpful.[54]

Self-adhesive pads are most effective for reducing thick lesions, whereas lotions, creams, and medicaments in petrolatum are best for maintenance. Most salicylic acid compounds are 10-17%. High concentrations of salicylic acid (eg, 40%) may lead to severe maceration, and in patients with diabetes, it may lead to frank foot ulcerations.[55] Intralesional triamcinolone and topical vitamin A acid compounds also may reduce localized hyperkeratosis. Triamcinolone can lead to localized hypopigmentation.[56]

A statistically significant reduction in pain at 6 months with complete and partial resolution rates of 26% and 50%, respectively, were seen with electrosurgery compared with resolution rates of 4% and 28%, respectively, with sharp debridement in one study.[57]

Soft corns are often difficult to treat because they develop from underlying pressures in between the fourth and fifth digit, caused by bony prominences.[5] Soft corns are best treated with properly fitting footwear and better foot hygiene in order to decrease the likelihood for infection. Applying an antifungal or antibacterial powder after washing the area and using lamb’s wool or a toe spacer are additional techniques used to treat soft corns.[8] A good option in patients with coexisting dermatophytosis complex is 20% aluminum chloride hexahydrate solution (Drysol).

Reduced friction may be accomplished with the use of silicone-lined sleeves on the toes, padding, and, in select cases, silicone[58] or collagen injections[6] over the bony prominence in question.

Lamb's wool may be beneficial in interdigital corns. Pads or permanent insoles, which place pressure proximal to the metatarsal head, relieve stress on the region. Insoles may be made of silicone or soft plastics.

Shoes with extra length are required for toe deformity, and shoes with extra width are required for lateral toe callosities. Shoes should be soft inside without seams that rub or press. Orthotics can be placed in the shoe for patients with abnormalities of the foot, such as cavovarus. Orthotics can be created by using insoles made to correct deformities noted on dynamic pressure molds. Reduction of heel height may be helpful for patients with metacarpal head callosities.[59]

Vacuum orthoses have been described to aid in lesional clearance for diabetic patients with plantar callosities.[60]

Following are additional treatment modalities:

Overall, removing or adjusting the mechanical stress causing the corn—finding footwear that matches the length and width of a foot—is the first step towards treatment of this condition.[6, 70] Patient awareness of his or her footwear is critical to the prevention of future corns. Conservative treatment can be continued at home and may consist of using a pumice stone for minor debridement, practicing good foot hygiene, and using soft spacers or a silicone sleeve, which can be bought at most retail stores.[5, 61]

Further inpatient care

Further inpatient care usually is not required unless surgical adjustments are needed.

A patient with diabetes who has neuropathic ulcers and overlying clavus formation may require further care.

Rheumatoid arthritis patients may benefit more from surgical interventions than callous debridement. Forefoot arthroplasty and first metatarsophalangeal joint implants may improve clavus formation and rheumatoid foot pain over the long term.

Measurement of the foot for orthoses is beneficial in the case of multiple clavi.

Surgical Care

Surgery to remove the bony prominences is indicated only if all conservative measures fail.[6, 7, 27] Surgical procedures include bunionectomy, syndactylization, osteotomy, and arthroplasty.[5, 27] Long-term improvement for lateral fifth-toe corns and interdigital corns has been achieved with partial and complete condylectomy.[27]

Chronic foot pain despite conservative therapy is the number one indication for surgery.

Hallux valgus correction may aid in reduction of painful callosities over the long term.[60]

Surgical corrections for claw, hammer, and mallet toes are simple procedures.

Shaving of prominent condyles of bony prominences may be beneficial, particularly on the fifth digit.

Arthroplasty of the fifth toe interphalangeal joint also may be performed.

Metatarsal condylectomy or chevron osteotomy may be performed to relieve metatarsal head pressure.[71]

Mann and DuVries described the use of a combination of arthroplasty and condylectomy. This combination results in 95% clearance, with only a 13% occurrence of transfer lesions.[72]

When thinning of the plantar fat pads is contributory to the formations of callosities, injectable silicone can be used on the soles underneath the callosities and corns to reduce pressure-related callous formation.

Description of excision followed by either grafting, use of flaps, or grafting using split-thickness graft with or without a collagen/elastin matrix graft has been described as effective in a single resistant case.[72]

Consultations

If patients do not respond to conservative treatment, further evaluation by a podiatrist or orthopedic surgeon is recommended. Extensive orthoses are available to help remove mechanical stresses on the foot, and an orthopedist or podiatrist should be consulted.

An orthopedist and a podiatrist also can be helpful in adjusting abnormalities of gait or pressure distribution.

In cases of suspected arthritis, a rheumatologist can be consulted.

Dermatologists are best consulted to assess for the possibility of other disorders in the differential diagnosis, especially warts and keratoderma.

Diet

Weight loss may reduce pain from corns and improve biomechanics in patients who are obese.

Activity

Patients are advised to reduce or eliminate certain mechanical forces or motions. However, certain activities, particularly work related, may be unavoidable or patients may be reluctant to make the necessary changes.

Adjustment of the footwear and the use of special insoles aid in the maintenance of full mobility and eliminate the need for activity limitation.

Prevention

Deterrence and prevention includes the use of corn pads, web spacers, and properly fitting shoes (see Pathophysiology and Medical Care). Patients can treat their corns at home using a pumice stone to regularly debulk the lesion after a shower, when the skin is soft.

Long-Term Monitoring

Follow-up care is important to ensure control of the hyperkeratosis because patients may require regular, repeated applications of keratolytic agents in conjunction with careful paring.

Patients with special health concerns, including diabetic patients, amputees, and elderly persons, may require more frequent follow-up visits in order to decrease the likelihood of a more catastrophic complication, particularly secondary bacterial infection, from the initial lesion.

Numerous contributory factors may result in thickened skin on the feet. Factors such as occupation, athletic pursuits, footwear, underlying bony abnormalities, and problems with general health may contribute to clavus formation.

Etiologic factors must be carefully assessed before treatment can be given.

Symptomatic relief can be achieved by thinning the hyperkeratotic lesions and by using cushions or insoles, which reduce pressure on the affected areas.

Surgery can be an adjunctive treatment in those patients with intractable clavus formation and chronic foot pain.

Using a combination of modalities and reducing the pressure of footwear ultimately reduces the appearance and discomfort of the clavus.

Medication Summary

The goals of pharmacotherapy are to reduce morbidity and to prevent complications.

Debridement may be enhanced with the use of keratolytic agents, such as ureas, alpha-hydroxy acid (eg, glycolic, malic, or lactic acid), or beta-hydroxy acid (eg, salicylic acid). The use of these agents is not recommended in pregnant women and young children. Most salicylic acid compounds are 10-17%. High concentrations of salicylic acid (eg, 40%) may lead to severe maceration and frank foot ulcerations in patients with diabetes. Self-adhesive pads are most effective for reducing thick lesions, whereas lotions, creams, and medicaments in petrolatum are best for maintenance. Intralesional triamcinolone and topical vitamin A acid compounds also may reduce localized hyperkeratosis. Triamcinolone may be injected during pregnancy because of its limited absorption; however, it can lead to localized hypopigmentation. Topical vitamin A derivatives are not intended for use in women who are pregnant or intending to become pregnant because their safety ranges from category C to category X.

A combination product to be applied by physicians consisting of 1% cantharidin, a vesicant, mixed with 30% salicylic acid and 5% podophyllin has been described as effective for most people after just one session.[68]

Salicylic acid topical (Clear Away, Compound W, Dr. Scholl's Corn Removers)

Clinical Context:  Topical salicylic acid is a keratolytic, bacteriostatic, and fungistatic agent. Its main clinical use is as a keratolytic agent and as an agent that increases the percutaneous absorption of combined drugs by removing the stratum corneum. The keratolytic activity results from solubilization of the intercellular ground substance in the stratum corneum and shedding of the scales, which are bound by it.

Salicylic acid topical can be compounded in petrolatum at any percentage and is usually used at 5-20%, beginning with a lower percentage. It can be purchased over the counter as a liquid or pad preparation, ranging from 17-40% (multiple companies make these). It can be irritating or cause blistering.

Ammonium lactate (AmLactin, Lac-Hydrin, Lactinol)

Clinical Context:  Ammonium lactate may loosen the adhesion of the keratinocytes in the stratum corneum, thereby thinning the skin. Ammonium lactate provides beneficial effects on dry skin and severe hyperkeratotic conditions. It is indicated for moisturizing and softening dry, scaly skin.

Urea (Aquadrate, Calmurid, Carmol, Nutraplus)

Clinical Context:  Urea is a a keratolytic, bacteriostatic, bactericidal, and fungistatic agent. It is topical treatment for dry skin and ichthyosis and is also used as a skin moisturizer. Urea promotes the hydration and removal of excess keratin in conditions of hyperkeratosis.

Class Summary

These agents cause the cornified epithelium to swell, soften, macerate, and then desquamate. Commonly used agents include urea, alpha-hydroxy acids (eg, lactic acid, glycolic acid), and beta-hydroxy acids (eg, salicylic acid).

Triamcinolone (Aristospan, Kenalog IV, Trivaris)

Clinical Context:  An injectable version of triamcinolone is available in concentrations of 3-40 mg/mL. Generally, this compound is diluted to 1-4% for injection into lesions, such as a clavus.

Class Summary

These drugs have anti-inflammatory properties and cause profound and varied metabolic effects. Corticosteroids modify the body's immune response to diverse stimuli.

Tretinoin topical (Atralin, Avita, Refissa)

Clinical Context:  Tretinoin topical inhibits microcomedo formation and eliminates lesions. It makes keratinocytes in sebaceous follicles less adherent and easier to remove. It is available as 0.025%, 0.05%, and 0.1% creams and 0.01% and 0.025% gels.

Class Summary

These agents are not specifically approved for use in corn (clavus) therapy. Only tretinoin has been shown to be useful for clavus therapy in the topically applied form. These agents cause the skin to peel by loosening of keratinocyte adhesion. Irritation and discomfort are limiting adverse effects.

Author

Nanette B Silverberg, MD, Clinical Professor of Dermatology, Icahn School of Medicine at Mount Sinai; Chief of Pediatric Dermatology, Mt Sinai Health Systems, Mount Sinai St Luke's-Roosevelt Hospital and Mt Sinai Beth Israel Medical Centers

Disclosure: Received income in an amount equal to or greater than $250 from: Valeant Pharmaceuticals.

Specialty Editors

David F Butler, MD, Former Section Chief of Dermatology, Central Texas Veterans Healthcare System; Professor of Dermatology, Texas A&M University College of Medicine; Founding Chair, Department of Dermatology, Scott and White Clinic

Disclosure: Nothing to disclose.

Chief Editor

Dirk M Elston, MD, Professor and Chairman, Department of Dermatology and Dermatologic Surgery, Medical University of South Carolina College of Medicine

Disclosure: Nothing to disclose.

Additional Contributors

Amy Lynn Basile, DO, MPH, Sun Coast Hospital/Largo Medical Center

Disclosure: Nothing to disclose.

Daniel J Hogan, MD, Clinical Professor of Internal Medicine (Dermatology), Nova Southeastern University College of Osteopathic Medicine; Investigator, Hill Top Research, Florida Research Center

Disclosure: Nothing to disclose.

Richard K Scher, MD, Adjunct Professor of Dermatology, University of North Carolina at Chapel Hill School of Medicine; Professor Emeritus of Dermatology, Columbia University College of Physicians and Surgeons

Disclosure: Nothing to disclose.

Acknowledgements

The authors and editors of Medscape Reference gratefully acknowledge the contributions of previous authors Ali Hendi, MD; Douglas W. Kress, MD; and Roger Patrick, MD, to the development and writing of this article.

References

  1. Mann RA. Pain in the foot. 1. Evaluation of foot pain and identification of associated problems. Postgrad Med. 1987 Jul. 82 (1):154-7, 160-2. [View Abstract]
  2. Cheon JJ, Uhm JY, Kang GH, Kang EG, Kim SY, Chang SS. Evaluation of the dermatologic life quality among cleanroom workers in a secondary battery factory. Ann Occup Environ Med. 2016. 28 (1):39. [View Abstract]
  3. Freeman DB. Corns and calluses resulting from mechanical hyperkeratosis. Am Fam Physician. 2002 Jun 1. 65(11):2277-80. [View Abstract]
  4. Farndon L, Concannon M, Stephenson J. A survey to investigate the association of pain, foot disability and quality of life with corns. J Foot Ankle Res. 2015. 8:70. [View Abstract]
  5. Murphy GA. Lesser Toe Abnormalities: Corns (Helomata and Clavi). Canale ST, ed. Canale: Campbell's Operative Orthopaedics. 10th. St. Louis, Mo: Mosby; 2003. 4063-5.
  6. Singh D, Bentley G, Trevino SG. Callosities, corns, and calluses. BMJ. 1996 Jun 1. 312(7043):1403-6. [View Abstract]
  7. Snider RK. Corns and Calluses. Greene WB, ed. Essentials of Musculoskeletal Care. 2nd ed. Rosemont, Ill: American Academy of Orthopaedic Surgeons; 2001. 437-41.
  8. DeLauro TM, DeLauro NM. Corns and Calluses. Wolff K, Goldsmith LA, Katz SI, Gilchrest BA, Paller AS, Leffell DJ, eds. Fitzpatrick's Dermatology in General Medicine. 7th ed. New York, NY: McGraw-Hill; 2008. 97.
  9. Kennedy CTC, Burd DAR. Mechanical and Thermal Injury. Burns T, Breathnach SM, Cox N, Griffiths CE, eds. Rook's Textbook of Dermatology. 7th ed. London, England: Blackwell Science; 2004. 22.
  10. Viegas SF, Torres FG. Cherry pitter's thumb. Case report and review of the literature. Orthop Rev. 1989 Mar. 18 (3):336-8. [View Abstract]
  11. Villano PA, Ruocco V, Pisani M. The cameo engraver's corn. Int J Dermatol. 1990 Jul-Aug. 29 (6):424-5. [View Abstract]
  12. Scott MJ Jr, Scott NI, Scott LM. Dermatologic stigmata in sports: weightlifting. Cutis. 1992 Aug. 50 (2):141-5. [View Abstract]
  13. Mishriki YY. Skin commotion from repetitive devotion. Prayer callus. Postgrad Med. 1999 Mar. 105 (3):153-4. [View Abstract]
  14. O'Goshi KI, Aoyama H, Tagami H. Mucin deposition in a prayer nodule on the forehead. Dermatology. 1998. 196 (3):364. [View Abstract]
  15. Maharaj D, Naraynsingh V. Cigarette lighter thumb. Am J Med. 2001 Apr 15. 110 (6):506. [View Abstract]
  16. Kanerva L. Knuckle pads from boxing. Eur J Dermatol. 1998 Jul-Aug. 8 (5):359-61. [View Abstract]
  17. Daluiski A, Rahbar B, Meals RA. Russell's sign. Subtle hand changes in patients with bulimia nervosa. Clin Orthop Relat Res. 1997 Oct. 107-9. [View Abstract]
  18. Koh D, Jeyaratnam J, Aw TC. An occupational mark of screwdriver operators. Contact Dermatitis. 1995 Jan. 32 (1):46. [View Abstract]
  19. Heyl T, Raubenheimer EJ. Sucking pads (sucking calluses) of the lips in neonates: a manifestation of transient leukoedema. Pediatr Dermatol. 1987 Aug. 4 (2):123-8. [View Abstract]
  20. Gibbs RC. "Vamp disease". J Dermatol Surg Oncol. 1979 Feb. 5 (2):92-3. [View Abstract]
  21. Vaseenon T, Intharasompan P, Wattanarojanapom T, Theeraamphon N, Auephanviriyakul S, Phisitkul P. Foot and ankle problems in Muay Thai kickboxers. J Med Assoc Thai. 2015 Jan. 98 (1):65-70. [View Abstract]
  22. Patruno C, Napolitano M, La Bella S, Ayala F, Balato N, Cantelli M, et al. Instrument-related Skin Disorders in Musicians. Dermatitis. 2016 Jan-Feb. 27 (1):26-9. [View Abstract]
  23. Hirao M, Ebina K, Shi K, Tomita T, Noguchi T, Tsuboi H, et al. Association between preoperative pain intensity of MTP joint callosities of the lesser toes and fore-mid-hindfoot deformities in rheumatoid arthritis cases. Mod Rheumatol. 2017 Jan. 27 (1):50-53. [View Abstract]
  24. Goksugur N, Cakici H. A new computer-associated occupational skin disorder: Mousing callus. J Am Acad Dermatol. 2006 Aug. 55 (2):358-9. [View Abstract]
  25. Cox NH, Finlay AY. Callosities of crossed-leg sitting. Int J Dermatol. 2009 Nov. 48 (11):1266-7. [View Abstract]
  26. Williams ML, Elias PM. Enlightened therapy of the disorders of cornification. Clin Dermatol. 2003 Jul-Aug. 21(4):269-73. [View Abstract]
  27. Coughlin MJ, Kennedy MP. Operative repair of fourth and fifth toe corns. Foot Ankle Int. 2003 Feb. 24(2):147-57. [View Abstract]
  28. Menz HB, Zammit GV, Munteanu SE. Plantar pressures are higher under callused regions of the foot in older people. Clin Exp Dermatol. 2007 Jul. 32(4):375-80. [View Abstract]
  29. Erkek E, Koçak M, Bozdoğan O, Atasoy P, Birol A. Focal acral hyperkeratosis: a rare cutaneous disorder within the spectrum of Costa acrokeratoelastoidosis. Pediatr Dermatol. 2004 Mar-Apr. 21 (2):128-30. [View Abstract]
  30. Manalo FB, Marks A, Davis HL Jr. Doxorubicin toxicity. Onycholysis, plantar callus formation, and epidermolysis. JAMA. 1975 Jul 7. 233 (1):56-7. [View Abstract]
  31. Oriba HA, Lo JS, Bergfeld WF. Callused feet, thick nails, and white tongue. Pachyonychia congenita. Arch Dermatol. 1991 Jan. 127 (1):113-4, 116-7. [View Abstract]
  32. Wollina U, Mohr F, Schier F. Unilateral hyperhidrosis, callosities, and nail dystrophy in a boy with tethered spinal cord syndrome. Pediatr Dermatol. 1998 Nov-Dec. 15 (6):486-7. [View Abstract]
  33. Robbins JM, Ballew KK, Lowery CR, Husni EA. Asymptomatic occlusive arterial disease. A case report. J Am Podiatr Med Assoc. 1985 Nov. 75 (11):616-8. [View Abstract]
  34. Coughlin MJ. Common causes of pain in the forefoot in adults. J Bone Joint Surg Br. 2000 Aug. 82(6):781-90. [View Abstract]
  35. Verbov JL, Monk CJ. Talar callosity--a little-recognized common entity. Clin Exp Dermatol. 1991 Mar. 16 (2):118-20. [View Abstract]
  36. Oztekin HH, Boya H, Nalcakan M, Ozcan O. Second-toe length and forefoot disorders in ballet and folk dancers. J Am Podiatr Med Assoc. 2007 Sep-Oct. 97 (5):385-8. [View Abstract]
  37. Baccouche D, Mokni M, Ben Abdelaziz A, Ben Osman-Dhahri A. [Dermatological problems of musicians: a prospective study in musical students]. Ann Dermatol Venereol. 2007 May. 134 (5 Pt 1):445-9. [View Abstract]
  38. Gambichler T, Uzun A, Boms S, Altmeyer P, Altenmüller E. Skin conditions in instrumental musicians: a self-reported survey. Contact Dermatitis. 2008 Apr. 58 (4):217-22. [View Abstract]
  39. Verma SB, Wollina U. Callosities of cross legged sitting: "yoga sign"--an under-recognized cultural cutaneous presentation. Int J Dermatol. 2008 Nov. 47 (11):1212-4. [View Abstract]
  40. Darvall WA. Flash dancing and spine bumps. Med J Aust. 1984 Apr 28. 140 (9):568. [View Abstract]
  41. Lemont H, Ravick A. Hemorrhage within plantar callus. A cutaneous sign of rheumatoid angiitis. J Am Podiatry Assoc. 1980 Jan. 70 (1):22-5. [View Abstract]
  42. Murray HJ, Young MJ, Hollis S, Boulton AJ. The association between callus formation, high pressures and neuropathy in diabetic foot ulceration. Diabet Med. 1996 Nov. 13 (11):979-82. [View Abstract]
  43. Dunn JE, Link CL, Felson DT, Crincoli MG, Keysor JJ, McKinlay JB. Prevalence of foot and ankle conditions in a multiethnic community sample of older adults. Am J Epidemiol. 2004 Mar 1. 159(5):491-8. [View Abstract]
  44. Menz HB, Morris ME. Footwear characteristics and foot problems in older people. Gerontology. 2005 Sep-Oct. 51(5):346-51. [View Abstract]
  45. Black JR, Hale WE. Prevalence of foot complaints in the elderly. J Am Podiatr Med Assoc. 1987 Jun. 77(6):308-11. [View Abstract]
  46. Benvenuti F, Ferrucci L, Guralnik JM, Gangemi S, Baroni A. Foot pain and disability in older persons: an epidemiologic survey. J Am Geriatr Soc. 1995 May. 43(5):479-84. [View Abstract]
  47. Habif TP. Warts, Herpes Simplex and other Viral Infections. Clinical Dermatology: A Color Guide to Diagnosis and Therapy. 4th ed. St. Louis, Mo: Mosby; 2004. 374-5.
  48. Mann RA, DuVries HL. Intractable plantar keratosis. Orthop Clin North Am. 1973 Jan. 4(1):67-73. [View Abstract]
  49. Bae JM, Kang H, Kim HO, Park YM. Differential diagnosis of plantar wart from corn, callus and healed wart with the aid of dermoscopy. Br J Dermatol. 2009 Jan. 160(1):220-2. [View Abstract]
  50. Kurvin L, Volkering C. [Diagnosis and treatment of warts, corns, and clavi]. MMW Fortschr Med. 2007 Mar 8. 149 (10):31-3. [View Abstract]
  51. Dainichi T, Honma Y, Hashimoto T, Furue M. Clavus detected incidentally by positron emission tomography with computed tomography. J Dermatol. 2008 Apr. 35 (4):242-3. [View Abstract]
  52. Sage RA, Webster JK, Fisher SG. Outpatient care and morbidity reduction in diabetic foot ulcers associated with chronic pressure callus. J Am Podiatr Med Assoc. 2001 Jun. 91(6):275-9. [View Abstract]
  53. Thomas JR 3rd, Doyle JA. The therapeutic uses of topical vitamin A acid. J Am Acad Dermatol. 1981 May. 4 (5):505-13. [View Abstract]
  54. Dehghani F, Merat A, Panjehshahin MR, Handjani F. Healing effect of garlic extract on warts and corns. Int J Dermatol. 2005 Jul. 44 (7):612-5. [View Abstract]
  55. Foster A, Edmonds ME, Das AK, Watkins PJ. Corn cures can damage your feet: an important lesson for diabetic patients. Diabet Med. 1989 Dec. 6(9):818-9. [View Abstract]
  56. George WM. Linear lymphatic hypopigmentation after intralesional corticosteroid injection: report of two cases. Cutis. 1999 Jul. 64 (1):61-4. [View Abstract]
  57. Bevans JS, Bosson G. A comparison of electrosurgery and sharp debridement in the treatment of chronic neurovascular, neurofibrous and hard corns. A pragmatic randomised controlled trial. Foot (Edinb). 2010 Mar. 20(1):12-7. [View Abstract]
  58. Balkin SW. Injectable silicone and the foot: a 41-year clinical and histologic history. Dermatol Surg. 2005 Nov. 31(11 Pt 2):1555-9; discussion 1560. [View Abstract]
  59. Richards RN. Calluses, corns, and shoes. Semin Dermatol. 1991 Jun. 10(2):112-4. [View Abstract]
  60. Nagel A, Rosenbaum D. Vacuum cushioned removable cast walkers reduce foot loading in patients with diabetes mellitus. Gait Posture. 2009 Jul. 30 (1):11-5. [View Abstract]
  61. Cordoro KM, Ganz JE. Training room management of medical conditions: sports dermatology. Clin Sports Med. 2005 Jul. 24(3):565-98, viii-ix. [View Abstract]
  62. Stephenson J, Farndon L, Concannon M. Analysis of a trial assessing the long-term effectiveness of salicylic acid plasters compared with scalpel debridement in facilitating corn resolution in patients with multiple corns. J Dermatol. 2016 Jun. 43 (6):662-9. [View Abstract]
  63. Balkin SW. Silicone injection for plantar keratoses. Preliminary report. J Am Podiatry Assoc. 1966 Jan. 56(1):1-11. [View Abstract]
  64. Field LM. Letter: injectable silicone for painful interdigital neurovascular clavi and verrucae. Dermatol Surg. 2006 Dec. 32(12):1535. [View Abstract]
  65. Narins RS, Beer K. Liquid injectable silicone: a review of its history, immunology, technical considerations, complications, and potential. Plast Reconstr Surg. 2006 Sep. 118(3 Suppl):77S-84S. [View Abstract]
  66. Brousseau-Foley M, Cantin V. Digital and interdigital corns: a report of two cases with use of hyaluronic acid gel filler. J Am Podiatr Med Assoc. 2014 Jul. 104(4):413-6. [View Abstract]
  67. McDowell BA. Carbon dioxide laser excision of benign pedal lesions. Clin Podiatr Med Surg. 1992 Jul. 9 (3):617-32. [View Abstract]
  68. Akdemir O, Bilkay U, Tiftikcioglu YO, Ozek C, Yan H, Zhang F, et al. New alternative in treatment of callus. J Dermatol. 2011 Feb. 38 (2):146-50. [View Abstract]
  69. González-Ramos J, Sendagorta-Cudós E, González-López G, Mayor-Ibarguren A, Feltes-Ochoa R, Herranz-Pinto P. Efficacy of botulinum toxin in pachyonychia congenita type 1: report of two new cases. Dermatol Ther. 2016 Jan-Feb. 29 (1):32-6. [View Abstract]
  70. Dockery GL, Nilson RZ. Intralesional injections. Clin Podiatr Med Surg. 1986 Jul. 3(3):473-85. [View Abstract]
  71. Lee KB, Park JK, Park YH, Seo HY, Kim MS. Prognosis of painful plantar callosity after hallux valgus correction without lesser metatarsal osteotomy. Foot Ankle Int. 2009 Nov. 30 (11):1048-52. [View Abstract]
  72. Atlan M, Naouri M, Lorette G, Estève E, Zakine G. [Original treatment of constitutional painful callosities by surgical excision, collagen/elastin matrix (MatriDerm(®)) and split thickness skin graft secured by negative wound therapy]. Ann Chir Plast Esthet. 2011 Apr. 56 (2):163-9. [View Abstract]

Hard corn over the proximal interphalangeal joint of second toe. Courtesy of James K. DeOrio, MD.

Calluses on the palmar surface of the hands of a body builder. Courtesy of James K. DeOrio, MD.

Screwdriver operator's callus (ie, clavus).

Hard corn on the lateral surface of fifth toe. Courtesy of James K. DeOrio, MD.

Hard corn on the lateral surface of fifth toe. Courtesy of James K. DeOrio, MD.

Hard corn over the proximal interphalangeal joint of second toe. Courtesy of James K. DeOrio, MD.

Calluses on the palmar surface of the hands of a body builder. Courtesy of James K. DeOrio, MD.

Screwdriver operator's callus (ie, clavus).

Vernacular Term Location Association
Jeweler's callus, cherry pitter's thumb,[10] cameo engraver's corn[11] ThumbDigital changes, including callosities related to repetitive use of fine jeweler's instruments, which also may be seen with the use of cherry-pitting tools
Weight lifter's callus[12] Callosities over the palmar metacarpophalangeal jointsCaused by the friction of weight-lifting apparatus (This also may be seen in athletes who participate in crew.)
Prayer callus[13, 14] Callosity on the foreheadFrom kneeling prayer with the hands on the forehead
Cigarette lighter's thumb[15] Hyperkeratosis of the radial aspect of the thumbCaused by excessive cigarette lighter flicking
Knuckle pads[16] Hyperkeratosis over the knucklesCaused by boxing training
Russell sign[17] Callosities of the dorsum of the hand over the metacarpophalangeal and interphalangeal jointsCaused by the friction involved with self-induced emesis in bulimia nervosa
Screwdriver operator's clavus[18] Palmar surface of the handOccurs at the site of contact with a screwdriver handle
Spine bumpsHyperkeratosis over the spinal columnCaused by dancing with spinning on one's back
Hairdresser's handFirst finger on dominant handCallus formation at the site of friction caused by scissors around the first finger on the dominant hand
Sucking calluses[19] Lip, hand, or foot of a newbornCallus formation at the site of an area of suction on the lip, hand, or foot of a newborn
Vamp disease[20] FeetClavus formation due to wearing tight high-heeled shoes
Muay Thai kickboxers[21] FeetCallosities on the forefoot (77.5%), on the plantar first metatarsal (55.3%), and on the big toe (33.3%)