What are the skin findings associated with plantar wart (verruca plantaris)?

From the Guidelines

Plantar warts are typically characterized by small, rough growths on the soles of the feet, often with a well-defined border and a rough, grainy surface, and may be painful when pressure is applied during walking or standing. These warts can appear as a single lesion or in clusters (mosaic warts) and frequently develop on weight-bearing areas like the heels or balls of the feet 1. The skin around plantar warts may become thickened due to pressure, and the wart itself might grow inward beneath a thick callus. Unlike normal skin lines which go around these lesions, skin lines are interrupted at the wart site.

Key Characteristics of Plantar Warts

• Small, rough growths on the soles of the feet
• Well-defined border and rough, grainy surface
• Painful when pressure is applied during walking or standing
• May appear as a single lesion or in clusters (mosaic warts)
• Frequently develop on weight-bearing areas like the heels or balls of the feet
• Skin around the wart may become thickened due to pressure
• Wart may grow inward beneath a thick callus
• Skin lines are interrupted at the wart site Plantar warts are caused by human papillomavirus (HPV) types 1,2,4, or 63, which enters the skin through tiny cuts or breaks 1. The virus thrives in warm, moist environments, making swimming pools and communal showers common sources of infection. People with compromised immune systems are more susceptible to developing these warts, which can persist for months to years if left untreated. According to a study published in the British Journal of Dermatology, the cure rate for plantar warts is relatively low, with a mean cure rate of 49% 1.

Causes and Risk Factors

• Caused by human papillomavirus (HPV) types 1,2,4, or 63
• Enters the skin through tiny cuts or breaks
• Thrives in warm, moist environments
• Common sources of infection include swimming pools and communal showers
• People with compromised immune systems are more susceptible to developing plantar warts It is essential to note that the treatment of plantar warts can be challenging, and the effectiveness of various treatments may vary 1. A combination of salicylic acid and cryotherapy may be the most effective treatment option for plantar warts, but the cure rate is still relatively low. Therefore, it is crucial to consult a healthcare professional for proper diagnosis and treatment.

From the FDA Drug Label

For Dermatologic Use: Salicylic Acid 6% is a topical aid in the removal of excessive keratin in hyperkeratotic skin disorders including verrucae, and the various ichthyoses (vulgaris, sex-linked and lamellar), keratosis palmaris and plantaris keratosis pilaris, pityriasis rubra pilaris, and psoriasis (including body, scalp, palms and soles). For Podiatric Use: Salicylic Acid 6% is a topical aid in the removal of excessive keratin on dorsal and plantar hyperkeratotic lesions. Topical preparations of 6% salicylic acid have been reported to be useful adjunctive therapy for verrucae plantares.

The skin findings for plantar warts include hyperkeratotic lesions on the plantar surface of the foot.

• Verrucae plantares are a type of hyperkeratotic skin disorder that can be treated with salicylic acid 6% 2.
• The key words associated with plantar wart skin findings are verrucae, hyperkeratotic lesions, and plantar keratosis.

From the Research

Plantar Wart Skin Findings

• Plantar warts are refractory to any form of treatment, with high cure rates reported with a topical proprietary formulation consisting of 1% cantharidin, 5% podophyllotoxin, and 30% salicylic acid (CPS) 3
• Cryotherapy is a method widely used in the treatment of plantar warts, but there is no evidence that it is more effective than any topical treatment 3, 4
• Salicylic acid and cryotherapy were found to be equally effective for clearance of plantar warts in a randomized controlled trial 4
• A systematic review of larger studies suggests keratolytic agents and destructive treatments, in particular salicylic acid and cryotherapy, remain the primary treatments for plantar warts 5
• Topical treatment with a cantharidin-podophyllin-salicylic acid formulation has been shown to have a high cure rate of 97.82% for plantar warts 6
• A preliminary study found that applying a compounding of 1% cantharidin, 5% podophyllotoxin, and 30% salicylic acid (CPS) resulted in complete eradication of lesions in 15 patients with recalcitrant plantar warts, with no side effects 7

Treatment Options

• Topical keratolytic agents, such as salicylic acid, are a common treatment for plantar warts 5
• Cryotherapy is a destructive treatment that can be used to treat plantar warts 4, 5
• Cantharidin-podophyllin-salicylic acid formulation is a topical treatment that has been shown to be effective for plantar warts 3, 6, 7
• Laser therapies and intralesional treatments are also available, but may not be as effective as other treatments 5, 6

Efficacy of Treatments

• The average cure rates of different treatments for plantar warts vary: cryotherapy (45.61%), salicylic acid (13.6%), cantharidin-podophyllin-salicylic acid formulation (97.82%), laser (79.36%), topical antivirals (72.45%), intralesional bleomycin (83.37%), and intralesional immunotherapy (68.14%) 6
• First-choice treatments for common warts, such as cryotherapy and salicylic acid, have low-cure rates for plantar warts 6