By Gary M. White, MD
The term, plantar, just means bottom of the foot. Thus, a plantar wart is a wart on the sole.
A hyperkeratotic papule or plaque on the sole is typical. They may be solitary or multiple, scattered or agminated. As noted above, they may coalesce forming a mosaic wart. When pared, the surrounding ring of keratin is often hard and thick while the central core is softer. At some point during paring, black dots and a fleshy core will appear. More paring at this point results in pinpoint bleeding and pain for the patient.
Warts need not be treated. PWs can be painful depending upon their thickness and location. The patient should be encouraged to do periodic paring if this is the case.
The wart may be treated alone with salicylic acid by the patient/parent. The patient/parent may be told to do the following:
"Do the following for any warts not on the face or anogenitals: Soak the wart in water for 5-10 minutes and then abrade the surface with e.g., a pumice stone or emery board, to remove the surface white layer. Let dry and then apply two to four drops of 17% salicylic acid (e.g., DuoFilm) directly to the wart once a day. Each drop should be permitted to dry before the next is added. Try to keep the salicylic acid off normal skin. When finished, you can cover with a bandage. Repeat daily. If the wart gets significantly inflamed (e.g., red and tender), hold treatment on that lesion and wait to see if the wart goes away. Sometimes when the body succeeds in killing the wart, the wart will suddenly turn black and then fall off in several days."
Alternatively, the application daily of salicylic acid and paring every 2-3 days is a helpful adjunct to cryotherapy. This is because lesions on the soles are driven deep into the skin by the pressure of walking. Removing the hyperkeratotic covering helps expose the wart to therapy. Some suggest the higher the concentration (going as high as 50%), the better. See also combination of SA and imiquimod below in imiquimod section.
The combination of 5-FU and SA is an effective and beneficial therapy for common and plantar warts [J Dtsch Dermatol Ges. 2004 Mar;2(3):187-93]. WartPeel is one such product.
For these and a variety of other treatment options, see verruca.
Often, plantar warts are resistant to cryotherapy. One useful technique is to anesthetize first with lidocaine (warn patients that this is painful) and then use a disposable, very sharp curette to core out the wart. Bleeding will occur but can be controlled with light electrocautery or a topical hemostatic agent (e.g., aluminum chloride). Then, a light freeze to the base should be done. This procedure is more aggressive and the patient should agree to the increased pain and longer healing time. S/he should be told of the hole that is created and the potential for limping for a few days. Due to the longer healing time, this procedure may be repeated monthly.
In a study comparing 5% 5-FU cream under tape occlusion versus tape occlusion alone in 40 patients with plantar warts [J Drugs Dermatol. 2006 May;5(5):418-24], the following was found: "Nineteen out of 20 patients (95%) randomized to 5% 5-FU with tape occlusion had complete eradication of all plantar warts within 12 weeks of treatment. The average time to cure occurred at 9 weeks of treatment. Three patients (15%) had a recurrence at the 6-month follow-up visit; accordingly, an 85% sustained cure rate was observed. It is concluded that use of topical 5% 5-fluorouracil cream for plantar warts is safe, efficacious, and accepted by the patient."
In a study of 50 patients with 424 plantar warts treated with adapalene gel 0.1% twice daily under occlusion using plastic wrap or weekly cryotherapy [Indian J Dermatol. 2015;60;102], the following was found: all the warts in 24 of 25 patients treated with adapalene disappeared in an average of 37 ± 19 days. All the warts in 24 of 25 patients treated with cryotherapy disappeared in 52 ± 30 days in an average of 1.88 sittings of cryo-therapy. During the study, the patients were seen weekly and and it appears from the report that paring was done at those visits. Also, the cryotherapy was performed for 1-2 minutes using an N2O gas operated machine at a temperature of −94°C. The authors postulate that the treatment works by inducing cell-mediated immunity against the wart [see Indian J Dermatol. 2011;56;513].
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