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Corns and Calluses
7 Interesting Facts of Corns and Calluses
- •Corns and calluses are typically caused by thickening of the keratin layers of the epidermis due to excessive pressure exerted over a bony prominence of the foot.
- •Loss of the normal fat pad, improper footwear, toe deformities, increased activity level, and systemic diseases (rheumatoid arthritis) may contribute to the development of corns and calluses.
- •Callus refers to a large lesion with undefined boundaries and without a central core.
- •Corn refers to a smaller lesion with well-defined boundaries and a central core. Corns are divided into hard and soft corns.
- •Nonoperative treatment consists of modifying footwear, paring the excessive keratin layers, and applying padding to alleviate pressure. Patient education is also important.
- •Surgery may be indicated to correct bony deformity.
- •Corns and calluses have a tendency to recur unless the underlying pathology is properly addressed.
History
- •Discomfort in normal footwear or when walking barefoot (advanced corn)
- •Inquire about a history of Charcot-Marie-Tooth disease, other neurologic conditions (such as diabetic neuropathy), or systemic disease (rheumatoid arthritis), as these can be causes for the toe deformities associated with corns and calluses.
- •May also be associated with older age, female gender, hallux valgus, and prolonged standing.
Physical Examination
- •Observation
- •Calluses are typically located on the plantar aspect of foot, mainly at the metatarsophalangeal joints, but may occur anywhere bony prominence exists.
- •Hard corns are commonly located on the fibular aspect of the fifth toe or dorsal aspect of the proximal interphalangeal (IP) or the distal interphalangeal (DIP) joints.
- •May be associated with hammertoe, mallet toe, or claw toe deformity
- •Hyperkeratotic area with a lighter conical center (without underlying vessels)
- •Soft corns present as maceration between the lesser toes, mainly between 4 and 5.
- •A result of the absorption of extreme amounts of moisture from perspiration
- •Sometimes reddish in appearance and may become infected
- •These may be extremely painful.
- Palpation
- •Hard and soft corns eventually become tender.
Imaging
- •Usually not necessary for initial treatment; clinical diagnosis
- •Radiographs: weight-bearing anteroposterior, lateral, and oblique views of the foot
- •In the case of an ulcerated lesion, may be used to identify osteomyelitis
- •Helpful to view the structural deformities as the cause of the callus or corn
Differential Diagnosis
- •Plantar warts: fine capillaries perpendicular to the surface, exhibit punctuate bleeding after trimming
- •Skin ulceration: skin layer is destroyed and exposes underlying soft tissues or bone.
- •Mycotic infection
Treatment
- •At diagnosis
- •Conservative management is appropriate.
- •Reduction of hyperkeratotic area by paring with a scalpel
- •Footwear adaptations (soft-soled shoes with large toe box)
- •Padding of the symptomatic area or to offload excess pressure
- •Toe sleeves or toe crests for dorsal corns on the IP joints of the toes
- Instruct patient how to shave the callus/corn with pumice stone after soaking in warm water.
- •Beware of salicylic acid on immunocompromised or neuropathic patients, as this can damage otherwise healthy skin.
- •Conservative management is appropriate.
- •Later
- •If the corn or callus cannot be controlled by conservative measures, surgical intervention may be warranted to correct underlying deformity.
When to Refer
- •Failure of conservative measures warrants referral to an orthopaedic surgeon. In addition, concern for infection warrants referral.
- •Surgical options include correction of the toe deformity and isolated condylectomy.
- •Deformity correction varies based on the location of deformity (metatarsal shortening osteotomy for plantar callus vs. hammertoe correction for DIP/IP corns).
- •If the examiner is not confident in excluding a true mycotic infection, referral to a dermatologist can be considered.
Prognosis
- •Generally good when there is no infection associated with osteomyelitis
Troubleshooting
- •Complications include bleeding after trimming the corn or callus, mycotic infection when maceration is not managed adequately, and, in rare cases, deeper infection with osteomyelitis of the phalanx.
- •Infection with swelling, redness, and warmth of the toe combined with pain is an absolute indication for immediate referral. Under such circumstances, intravenous antibiotic therapy should be considered.
Patient Instructions
- •Patients should be educated about the causes of corns and calluses.
- •Shoes should have a wide toe box, be free of any seams over the areas of callus/corn, and be appropriately sized.
- •Patients must be instructed in the use of a pumice stone to trim calluses without injuring healthy skin.
Seek Additional Information
- Freeman DB: Corns and calluses resulting from mechanical hyperkaratosis. Am Fam Phys 2002; 65-11: pp. 2277-2280.
- Jakeman A: The effective management of hyperkeratosis. Wound Essentials 2012; 1: pp. 65-73.
- Spink MJ, Menz HB, Lord SR: Distribution and correlates of plantar hyperkeratotic lesions in older people. J Foot Ankle Res 2009; 2: pp. 8.
- Tlougan BE, Mancini AJ, Mandell JA, et al.: Skin conditions in figure skaters, ice-hockey players and speed skaters: part 1—mechanical dermatoses. Sports Med 2011; 41 (9): pp. 709-719.