This chapter discusses the common foot disorders that are likely to present to the ED. Patients with chronic or complicated foot problems generally should be referred to a dermatologist, orthopedist, general surgeon, or podiatrist, depending on the disease and local resources. Tinea pedis, foot ulcers, and onychomycosis are discussed in Section 20, "Skin Disorders," in the chapter titled, "Disorders of the Hands, Feet, and Extremities." Puncture wounds of the foot are discussed in Section 6, "Emergency Wound Management," in the chapter titled, "Puncture Wounds and Bites." Foot ulcers and osteomyelitis are discussed in Section 17, "Endocrine Emergencies," in the chapter titled, "Type 2 Diabetes Mellitus."
Calluses are a thickening of the outermost layer of the skin and are a result of repeated pressure or irritation. Corns (clavus) develop similarly, but have a central hyperkeratotic core that is often painful. The causes can be external (poorly fitted shoe) or internal (bunion).
Calluses are protective and should not be treated if they are not painful. Calluses grow outward but may be pushed inward by continued pressure and become corns. Corns also develop in areas of scarring and between toes. Corns are classified as hard or soft. Hard corns are seen over bony protuberances where the skin is dry. Soft corns are seen between toes where the skin is moist. Corns may be painful or painless, but pressure on the corn usually produces pain. Diagnosis is based on clinical appearance. Corns interrupt the normal dermal lines and can thus be differentiated from calluses, which do not interrupt the normal dermal lines. Hard corns may resemble warts. However, when warts are pared, warts contain black seeds, which are thrombosed capillaries and may bleed, while corns do not bleed. Soft corns resemble tinea, and identifying tinea is important for proper treatment (see chapter titled, "Disorders of the Hands, Feet, and Extremities").1,2
Keratotic lesions may indicate more severe underlying disease, deformity, local foot disorder, or mechanical problem. Differential diagnosis of keratotic lesions includes syphilis, psoriasis, arsenic poisoning, rosacea, lichen planus, basal cell nevus syndrome, and, rarely, malignancies.2
Treatment of symptomatic corns often necessitates referral to a podiatrist because the treatment may involve repeated paring, use of keratolytic agents, and possibly surgery to correct any underlying source of pressure (bunion).1–4 Salicylic acid treatments are more effective than paring with a scapel.5 Recurrence can be prevented by weekly gentle trimming with a pumice stone or emery board after soaking in warm water for 20 minutes. Placing a pad on or around the lesion relieves pressure, and avoiding constrictive footwear also provides benefit.
Plantar warts are caused by the human papillomavirus. Plantar warts are most common in children, young adults, and butchers or fishmongers. Infection occurs by skin-to-skin contact, with maceration or sites of trauma. The incubation ...