For the past six months I have been treating plantar warts on the foot of a 20-year-old woman. After two Histofreeze treatments, the warts appeared diminished, but then at the third visit, the patient presented with six new warts in the same area. What do you suggest in this situation?
—FRANCES ROBINE, ARNP, Cape Coral, Fla.

Plantar warts can be refractory to attempted therapeutic interventions. Some of the agents and modalities that have been used include: 5-aminolevulinic acid (followed by photodynamic therapy), bleomycin (injection), cantharone, contact sensitizers (e.g., dinitrochlorobenzene or intralesional or topical Candida, mumps, or Trichophyton antigen), cryotherapy, curettage and cautery, dichloroacetic acid, duct tape (after soaking in water), 5-fluorouracil, formaldehyde, glutaraldehyde, imiquimod, lasers, retinoic acid, podofilox acid, podophyllin, salicylic acid, surgery, and trichloroacetic acid (Dermatol Nurs. 2007;19:372-375 and Nurs Stand. 2006;20:50-54). A superlative and comprehensive review of treatment options for warts appeared in Clin Med Res. 2006;4:273-293 (available online at: www.clinmedres.org/cgi/content/full/4/4/273, accessed July 2, 2008). However, evidence-based evaluations of the management of cutaneous warts demonstrate that no single therapy is virucidal or uniformly effective at achieving complete remission in every patient (Am Fam Physician. 2005;72:647-652 [available online at: www.aafp.org/afp/20050815/647.html, accessed July 2, 2008] and Am J Clin Dermatol. 2004;5:311-317). My approach to the treatment of plantar warts includes the daily application of a 40% salicylic acid pad (such as Mediplast) and twice-weekly pumice-stone paring of the lesion after soaking in water. If the warts persist without improvement after one month, I prescribe ranitidine 150 mg twice daily. At the initial and at monthly visits, I pare the warts (as tolerated by the patient) using a scalpel with a #15 blade. Most warts resolve within four to six months. Topical imiquimod 5% cream, initially every other night for the first one to two weeks and then nightly, is typically my next agent for treating plantar warts that persist.
—Philip R. Cohen, MD (118-3)