Corns (Clavus) Clinical Presentation

Updated: Jan 10, 2019
  • Author: Nanette B Silverberg, MD; Chief Editor: Dirk M Elston, MD  more...
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Presentation

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.

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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:

  • Both plantar warts and hard corns can be tender, and both occur on the pressure points of the sole.

  • Direct pressure generally causes tenderness in a callus and corn. Warts are tender with pressure applied from side to side. [7, 9]

  • Calluses have a waxy appearance after being pared, whereas corns produce a central keratin plug. [7] Plantar warts do not have a central core.

  • The absence of capillary dotting after paring hard corns distinguishes them from plantar warts. [6, 47]

  • Skin markings can be seen crossing the surface of calluses, but not warts or corns. [47]

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.

Hard corn on the lateral surface of fifth toe. Cou 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.

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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.

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