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PATIENT STORY

A 48-year-old woman with diabetes and mild sensory neuropathy presented with multiple calluses on the plantar feet (Figure 216-1). Most notably, the callus under the left hallux was hemorrhagic. Sharp debridement of the calluses was performed, and accommodating foot inserts to reduce pressure and friction on these calluses were dispensed. The patient walked out of the office with less pain and discomfort. She was instructed to watch out for hemorrhagic calluses, as they can have an underlying ulcer. One important goal, especially in a neuropathic patient, is to avoid such an ulcer (Figure 216-2), which occurred in another patient who did not get care for his callus in a timely manner.

FIGURE 216-1

Multiple calluses are found on the plantar feet. The callus in the left hallux can represent an underlying ulcer. A physician should be alerted when a callus is hemorrhagic, especially in a diabetic, neuropathic patient. (Reproduced with permission from Naohiro Shibuya, DPM.)

FIGURE 216-2

When neglected, an untreated hemorrhagic callus can turn into a full-thickness ulcer, which can result in infection in high-risk patients. (Reproduced with permission from Naohiro Shibuya, DPM.)

INTRODUCTION

Corns and calluses are localized, thickened epidermis, resulting from mechanical pressure or shearing force applied repeatedly on the same area. A callus is located on the plantar surface and "grows in." A corn is located on the dorsal surface or between digits and often "grows out." An ulcer forms if the plantar or interdigital lesion penetrates the subcutaneous layer. Initial management includes removing the pressure by changing shoes or using pads followed by sharp debridement if needed.

SYNONYMS

Hyperkeratotic lesion, keratosis, heloma durum (hard corn) or heloma molle (soft corn), tyloma (callus), clavi (corns).

EPIDEMIOLOGY

In one population-based study, 20% of men and 40% of women reported corns or calluses.1

ETIOLOGY AND PATHOPHYSIOLOGY

Calluses and corns are caused by multiple factors:

  • Mechanical pressure from abnormal biomechanics, underlying spur/exostosis, ill-fitting shoes, physiologic repetitive activities, and foot surgery or amputation that result in increased focal pressure at the distance site.

  • Shearing force from ill-fitting shoes, foot deformities (e.g., hammer toe and bunion), and physiologic repetitive activities.

  • A foreign body in the foot or shoe.

RISK FACTORS

  • Bunion (Figure 216-3), hammer toe, flatfoot, high-arched (cavus) foot, Charcot arthropathy (Figure 216-4).

  • Previous amputation in the foot (Figure 216-5).

  • Older age, fat pad atrophy.

  • Smoking.

  • Female gender.

  • Genodermatoses with abnormal keratin formation.

FIGURE 216-3

Bony prominences created by a bunion and hammertoe resulting in hyperkeratotic lesions ...

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