AUTHOR AND EDITOR INFORMATION

Section 1 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

INTRODUCTION

Section 2 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Background

Plantar warts are hyperkeratotic lesions on the plantar surface. They tend to develop over areas of pressure such as the heel and ball of the foot. Plantar warts are often endophytic (ie, they grow into the deeper layers of skin because of pressure). Although they are generally self-limited, plantar warts should be treated to lessen symptomatology, decrease duration, and reduce transmission.

Pathophysiology

Human papillomavirus (HPV), usually of type 1, 2, or 4, causes plantar warts. HPV attacks the epidermal layers through direct contact. See Human Papillomavirus.

Frequency

United States

Plantar warts are widespread; 7-10% of the population have warts.

Mortality/Morbidity

• Plantar warts may cause pain, particularly when walking.
• They may spread to other sites but not to histologically dissimilar areas (ie, plantar warts do not spread to genitalia).
• Most resolve spontaneously.

Sex

Plantar warts affect females slightly more often than males.

Age

Plantar warts may occur at any age, although they are more common in children and teenagers.

CLINICAL

Section 3 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

History

• Foot pain
• Leg or back pain (secondary to distortion or posture)

Physical

• Firm, hyperkeratotic lesions with tiny pinpoint petechiae centrally
• Smooth surface with a gray-yellow color
• Usually occur over areas of pressure or bony prominence such as the heel and ball of the foot
• Usually flat because of pressure
• Several warts may fuse to form mosaic warts
• Often difficult to differentiate warts from nonviral causes such as keratoses, lichen planus, molluscum contagiosum, corns, calluses, and foreign body or stress fractures
• • Hyperkeratotic tissue reveals typical punctate hemorrhages, which represent thrombosed capillaries of the papilloma.
  • Pathologic findings include acanthotic epidermis with hyperkeratosis.
  • Papillomatosis
  • Parakeratosis

Causes

Plantar warts are caused by direct exposure of HPV to the epidermis. This occurs through breaks in the stratum corneum of the epidermis. Such exposure frequently is associated with using public showers.¹

DIFFERENTIALS

Section 4 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Other Problems to be Considered

Corns
Calluses
Black heel (ruptured capillaries)

WORKUP

Section 5 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Lab Studies

• Diagnosis is typically made on clinical grounds.

TREATMENT

Section 6 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Emergency Department Care

Prompt treatment of plantar warts may ease patient suffering as well as prevent spread, transmission, and recurrence. However, plantar warts do not generally need emergent treatment. Treatment options include topical keratinolytic medications, cryotherapy, and surgery. Because plantar warts are epidermal, cautious treatment should not result in scarring. Reasonable options for the ED physician are as follows:

• Referral
• Topical keratinolytic and cauterizing agents
• • Salicylic acid, cantharidin, and dichloroacetic acid are useful.
  • Soak the affected area in warm water and dry it. Pare the top layer, and apply the chosen keratinolytic agent under tape occlusion.
  • Remove tape after 8 hours and file excess keratin (pumice stone works well for this purpose). Repeat the entire process daily or every other day for weeks until the plantar wart resolves.
• If the patient cannot comply with the protocol, simple acid application followed by occlusive taping for several days is occasionally effective. Several brands of salicylic acid pads are available as over-the-counter remedies.
• Oral therapy: One study showed improvement of plantar warts with the addition of zinc sulphate (10 mg/kg/d, maximum 600 mg).²
• Cryotherapy
• • Pare excessive keratin, taking care to go no further than the point where thrombosed capillaries are exposed. Freeze with a liquid nitrogen probe to produce a 2- to 3-mm margin.
  • Use a 1-minute freeze-thaw cycle. Successful cryotherapy usually requires 4-5 applications.
• Surgical
• • Dissection
  • Electrodesiccation
  • Curettage

Consultations

Dermatologists may provide immunotherapy for plantar warts resistant to initial interventions. Studies have shown very promising results with imiquimod, an immune response modifier.³

MEDICATION

Section 7 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Warts generally regress spontaneously within months or years. Because of the discomfort associated with plantar warts, removal is usually the best course. Keratolytic agents are usually applied topically to remove plantar warts.

Drug Category: Keratolytic agents

These agents cause the cornified epithelium to swell, soften, macerate, and then desquamate.

Drug Name	Cantharidin (Verr-Canth)
Description	Effectiveness against warts may result from exfoliation. Lytic action does not affect basal layer and has minimal effect on the corium. Scarring does not occur.
Adult Dose	Remove keratin covering wart; avoid cutting viable tissue; apply topically (wart and 1- to 3-mm around); allow to dry; secure with nonporous tape (protective cutout cushion over tape is helpful); patient may bathe and replace dressing in 24 h; debride in 1-2 wk; re-treat if viable wart tissue remains; >3 treatments for large lesions may be necessary
Pediatric Dose	Apply as in adults
Contraindications	Documented hypersensitivity; diabetes; impaired peripheral circulation; do not use on eyes, mucous membranes, anogenital or intertriginous areas, moles, birthmarks, or unusual warts with hair; do not use on lesions with other agents or if surrounding tissue is swollen or irritated
Interactions	None reported
Pregnancy	C - Safety for use during pregnancy has not been established.
Precautions	Strong vesicant to be used sparingly; not for use in the anogenital area; do not apply to eyes and mucosal tissue; avoid use in intertriginous sites due to problems with spreading and body occlusion, which often lead to more intense, painful reactions

Drug Name	Dichloroacetic acid (Bichloracetic Acid)
Description	Rapidly penetrates and cauterizes skin, keratin, and other tissues.
Adult Dose	Rub acid into the lesion with a pointed wood- or cotton-tipped applicator; 3-4 treatments may be necessary
Pediatric Dose	Apply as in adults
Contraindications	Documented hypersensitivity; malignant or premalignant lesions
Interactions	None reported
Pregnancy	C - Safety for use during pregnancy has not been established.
Precautions	Powerful keratolytic and cauterant; may cause severe burning, inflammation, or tenderness when applied to normal skin; apply only to lesion being treated (apply petrolatum around area to be treated to prevent this reaction); if any acid is spilled on normal tissue or if too much acid is applied, remove immediately and wash with water; sodium bicarbonate may be applied as local antidote

FOLLOW-UP

Section 8 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Complications

• Infection, pain, and scarring may result from overly aggressive therapy penetrating beneath the epidermis.
• If treatment is ineffective, pain may spread to other sites, and HPV may be transmitted to others.

Prognosis

• Plantar warts tend to recur.
• Plantar warts are not associated with malignancy.

Patient Education

• Use shower thongs or sandals, particularly in public shower rooms.
• For excellent patient education resources, visit eMedicine's Warts Center. Also, see eMedicine's patient education article Plantar Warts.

MISCELLANEOUS

Section 9 of 10  

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

Medical/Legal Pitfalls

• Remember that warts are not an emergency. Be cautious about using aggressive therapy.

REFERENCES

Section 10 of 10

• Authors and Editors
• Introduction
• Clinical
• Differentials
• Workup
• Treatment
• Medication
• Follow-up
• Miscellaneous
• References

1. Johnson LW. Communal showers and the risk of plantar warts. J Fam Pract. Feb 1995;40(2):136-8. [Medline].
2. Al-Gurairi FT, Al-Waiz M, Sharquie KE. Oral zinc sulphate in the treatment of recalcitrant viral warts: randomized placebo-controlled clinical trial. Br J Dermatol. Mar 2002;146(3):423-31. [Medline].
3. Skinner RB. Imiquimod. Dermatol Clin. Apr 2003;21(2):291-300. [Medline].
4. Allam JP, Hagemann T, Bieber T, Novak N. Successful treatment of therapy-resistant plantar verrucae vulgares with systemic interferon-beta. J Dermatol. Jul 2004;31(7):582-3. [Medline].
5. Esterowitz D, Greer KE, Cooper PH, Edlich RF. Plantar warts in the athlete. Am J Emerg Med. Jul 1995;13(4):441-3. [Medline].
6. Landsman MJ, Mancuso JE, Abramow SP. Diagnosis, pathophysiology, and treatment of plantar verruca. Clin Podiatr Med Surg. Jan 1996;13(1):55-71. [Medline].
7. Nelson WE, Behrman RE, Kliegman RM. Nelson Textbook of Pediatrics. 15^th ed. WB Saunders Co; 1995:1901-1903.
8. Nelson WE, Behrman RE, Kliegman RM. Nelson Textbook of Pediatrics. 14^th ed. WB Saunders Co; 1992:1901-1903.
9. Schroeter CA, Pleunis J, van Nispen tot Pannerden C,Reineke T, Neumann HA. Photodynamic therapy: new treatment for therapy-resistant plantar warts. Dermatol Surg. Jan 2005;31(1):71-5. [Medline].

Article Last Updated: Aug 2, 2007