Overview
Warts, or verrucae, are common viral infections that affect the epithelium of the skin and mucous membranes. They are caused by human papillomaviruses (HPVs).
Warts are defined according to their location. Common warts (verruca vulgaris) usually are found on the hands and fingers, but they also may occur on the face. Periungual warts and subungual warts occur around and underneath the nail beds, especially in nail biters and cuticle pickers. Juvenile (or flat) warts (verruca plana) usually occur on the face, neck, and dorsa of the hands, wrists, and knees of children. Venereal warts (condyloma lata and condyloma acuminata) typically occur near the genitalia and anus; the penile shaft is the most common site of lesions in men. Plantar warts (verruca plantaris) are common on the soles of the feet.
Only common warts and nonpainful plantar warts are amenable to self-treatment. Patients with other types of warts (including painful plantar warts) should be referred to a primary care provider.
Warts usually are not permanent. Approximately 23% clear spontaneously in 2 months, 30% clear spontaneously in 3 months, and 65%–78% clear in 2 years. The mechanism of spontaneous resolution is not fully understood.
Epidemiology
- Approximately 7%–10% of the general population has common warts.
- The peak incidence of warts occurs between the ages of 12 and 16 years.
- Plantar warts account for approximately 34% of all warts. Plantar warts are more common in older children, adolescents, and adults.
Etiology
- HPV infection occurs when the virus is inoculated into viable epidermis through defects in the epithelium. Inoculation can occur through person-to-person contact or autoinoculation to another body area.
- The presence of a heat-stable protein coat may allow the HPV to remain infectious outside the host cells for substantial periods of time.
- For warts to develop, the individual’s immune system must be susceptible to the virus.
- Immunodeficient patients maintained on immunosuppressive medications can develop widespread and highly resistant warts.
- Maceration of the skin is considered a contributing, predisposing factor, as demonstrated by the occurrence of plantar warts in individuals who frequent public swimming pools or use communal public showers.
- The incubation period after inoculation is 1–9 months, with an average of 3–4 months for a wart to become clinically apparent.
Signs and Symptoms
- Warts begin as minute, smooth-surfaced, skin-colored lesions that enlarge over time. Repeated irritation causes them to continue enlarging.
- Warts occasionally may be confused with more serious conditions, such as squamous cell carcinoma and deep fungal infections.
- A squamous cell carcinoma may develop rapidly, attaining a diameter of 1 cm within 2 weeks. The lesion generally appears as a small, red, conical, hard nodule that quickly ulcerates.
Common Warts
- Common warts are recognized by their rough, irregularly shaped, and domed appearance. They are slightly scaly, rough papules or nodules that appear alone or grouped.
- Common warts can be found on any skin surface, but they appear most often on the hands.
Plantar Warts
- Plantar warts are hyperkeratotic lesions generally associated with pressure. They usually are asymptomatic when small and may not be noticed.
- Plantar warts may occur on weight-bearing areas (the sole of the heel, the great toe, the areas below the heads of the metatarsal bones, and the ball of the foot) as well as non–weight-bearing areas on the sole of the foot.
- Plantar warts located on weight-bearing portions of the foot are under constant pressure and usually are not raised above the skin surface.
- The surface of the wart usually is grayish and friable, and the surrounding skin is thick and heaped.
- Several warts may coalesce and fuse, giving the appearance of one large wart (mosaic wart).
- The surface of the wart usually is grayish and friable, and the surrounding skin is thick and heaped.
- Pressure from walking may cause plantar warts that are large or occur on the heel or ball of the foot to be pushed inward. The lesion then impinges on the surrounding sensory nerve endings, causing discomfort or pain.
- Plantar warts may be confused with calluses, which also are found commonly on weight-bearing areas of the foot. (See Table 1 for a comparison of warts, calluses, and corns.)
Treatment
- Topical agents and procedures can relieve pain and sometimes help in removing warts. No single treatment is 100% effective.
- Because warts typically will regress spontaneously in 2 years, doing nothing is a valid management option if this approach is acceptable to the patient.
TABLE 1. Differentiation of Warts, Calluses, and Corns
Criterion | Warts | Calluses | Corns |
Location | Anywhere virus can gain entry into skin (e.g., hands, face, soles of the feet) | Usually over weight-bearing areas of foot | Usually over bony prominences of fourth and fifth toes, with hard corns occurring on tops of toes and soft corns in toe webs |
Signs |
