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A melanoma on the plantar surface of the foot can mimic a plantar wart.
Verrucous carcinoma, a slow-growing, locally invasive, well-differentiated SCC, also may be easily mistaken for a common or plantar wart.
DIAGNOSTIC TESTS & INTERPRETATION
Diagnosis
- HPV cannot be cultured, and lab testing is rarely necessary.
- Definitive HPV diagnosis can be achieved by the following:
- Electron microscopy
- Viral DNA identification employing Southern blot hybridization is used to identify the specific HPV type present in tissue
- Polymerase chain reaction may be used to amplify viral DNA for testing.
Follow-Up Tests & Special Considerations
Skin biopsy if unusual presentation or if diagnosis is unclear
Test Interpretation
- Histopathologic features of common warts include digitated epidermal hyperplasia, acanthosis, papillomatosis, compact orthokeratosis, hypergranulosis, dilated tortuous capillaries within the dermal papillae, and vertical tiers of parakeratotic cells with entrapped red blood cells above the tips of the digitations.
- In the granular layer, HPV-infected cells may have coarse keratohyaline granules and vacuoles surrounding wrinkled-appearing nuclei. These koilocytic (vacuolated) cells are pathognomonic for warts.
TREATMENT
- The abundance of therapeutic modalities described below is a reflection of the fact that none of them is uniformly or even clearly effective in trials. Placebo treatment response rate is significant and quality of evidence in general is poor. Beyond topical salicylates, there is no clear evidence-based rationale for choosing one method over another (1)[A].
- The choice of method of treatment depends on the following:
- Age of the patient
- Cosmetic and psychological considerations
- Relief of symptoms
- Patient 's pain threshold
- Type of wart
- Location of the wart
- Experience of the physician
GENERAL MEASURES
- There is no ideal treatment.
- In children, most warts tend to regress spontaneously.
- In many adults and immunocompromised patients, warts are often difficult to eradicate.
- Painful, aggressive therapy should be avoided unless there is a need to eliminate the wart(s).
- For surgical procedures, especially in anxious children, pretreat with anesthetic cream such as EMLA (emulsion of lidocaine and prilocaine).
MEDICATION
First Line
- Self-administered topical therapy
- Keratolytic (peeling) agents: The affected area(s) should be hydrated first by soaking in warm water for 5 minutes before application. Most over-the-counter agents contain salicylic acid and/or lactic acid; agents such as Duofilm, Occlusal-HP, Trans-Ver-Sal, and Mediplast.
- Office-based
- Cantharidin 0.7%, an extract of the blister beetle that causes epidermal necrosis and blistering
- Combination cantharidin 1%, salicylic acid 30%, and podophyllin resin 5% in flexible collodion; applied in a thin coat, occluded 4 to 6 hours, then washed off.
Second Line
Home-based
- Imiquimod 5% (Aldara) cream, a local inducer of interferon, is applied at home by the patient. It is approved for external genital and perianal warts and is used off-label and may be applied to warts under duct tape occlusion. It is applied at bedtime and washed off after 6 to 10 hours. Applied to flat warts without occlusion.
- Topical retinoids (e.g., tretinoin 0.025 " 0.1% cream or gel) for flat warts
Office-based
- Immunotherapy: induction of delayed type hypersensitivity with the following:
- Diphenylcyclopropenone (DCP) (2)[B]
- Dinitrochlorobenzene (DNCP)
- Squaric acid dibutylester (SADBE): There is possible mutagenicity and side effects with this agent.
- Intralesional injections
- Mumps or Candida antigen
- Bleomycin: Intradermal injection is expensive and usually causes severe pain.
- Interferon-α-2b
- Oral therapy
- Oral high-dose cimetidine: possibly works better in children
- Acitretin (an oral retinoid)
- Other treatments (all have all been used with varying results)
- Dichloroacetic acid, trichloroacetic acid, podophyllin, formic acid, aminolevulinic acid in combination with blue light, 5-fluorouracil, silver nitrate, formaldehyde, levamisole, topical cidofovir (3)[B] or IV cidofovir for recalcitrant warts in the setting of HIV, and glutaraldehyde
- The quadrivalent HPV vaccine has cleared recalcitrant, chronic oral, and cutaneous warts (4)[C].
COMPLEMENTARY & ALTERNATIVE MEDICINE
- Duct tape: Cover wart with waterproof tape (e.g., duct tape). Leave the tape on for 6 days, and then soak, pare with emery board, and leave uncovered overnight; then reapply tape cyclically for eight cycles; 85% resolved compared with 60% efficacy with cryotherapy (5)[A].
- Hyperthermia: safe and inexpensive approach; immerse affected area into 45 °C water bath for 30 minutes 3 times per week
- Hypnotherapy
- Raw garlic cloves have demonstrated some antiviral activity.
- Vaccines are currently in development.
Pregnancy Considerations
The use of some topical chemical approaches may be contraindicated during pregnancy or in women who are likely to become pregnant during the treatment period.
SURGERY/OTHER PROCEDURES
- Cryotherapy with liquid nitrogen (LN2) may be applied with a cotton swab or with a cryotherapy gun (Cryogun). Aggressive cryotherapy may be more effective than salicylic acid (6)[A], but it is associated with increased adverse effects (blistering and scarring):
- Best for warts on hands; also during pregnancy and breastfeeding
- Fast; can treat many lesions per visit
- Painful; not tolerated well by young children
- Freezing periungual warts may result in nail deformation.
- In darkly pigmented skin, treatment can result in hypo- or hyperpigmentation.
- Light electrocautery with or without curettage
- Best for warts on the knees, elbows, and dorsa of hands
- Also good for filiform warts
- Tolerable in most adults
- Requires local anesthesia
- May cause scarring
- Photodynamic therapy: Topical 5-aminolevulinic acid is applied to warts followed by photoactivation (7)[B].
- CO2 or pulse-dye laser ablation: expensive and requires local anesthesia
- For filiform warts: Dip hemostat into LN2 for 10 seconds, then gently grasp the wart for 10 seconds and repeat. Wart sheds in 7 to 10 days.
ONGOING CARE
FOLLOW-UP RECOMMENDATIONS
Patient Monitoring
1/3 of the warts of epidermodysplasia may become malignant.
PROGNOSIS
- More often than not (especially in children), warts tend to "cure " themselves over time.
- In many adults and immunocompromised patients, warts often prove difficult to eradicate.
- Rarely, certain types of lesions may transform into carcinomas.
COMPLICATIONS
- Autoinoculation (pseudo-Koebner reaction)
- Scar formation
- Chronic pain after plantar wart removal or scar formation
- Nail deformity after injury to nail matrix
REFERENCES
11 Kwok CS, Gibbs S, Bennett C, et al. Topical treatments for cutaneous warts. Cochrane Database Syst Rev. 2012;12;(9):CD001781.22 Choi Y, Kim do H, Jin SY, et al. Topical immunotherapy with diphenylcyclopropenone is effective and preferred in the treatment of periungual warts. Ann Dermatol. 2013;25(4):434 " 439.33 Fern ‘ndez-Morano T, del Boz J, Gonz ‘lez-Carrascosa M, et al. Topical cidofovir for viral warts in children. J Eur Acad Dermatol Venereol. 2011;25(12):1487 " 1489.44 Cyrus N, Blechman AB, Leboeuf M, et al. Effect of quadrivalent human papillomavirus vaccination on oral squamous cell papillomas. JAMA Dermatol. 2015;151(12):1359 " 1363.55 Wenner R, Askari SK, Cham PM, et al. Duct tape for the treatment of common warts in adults: a double-blind randomized controlled trial. Arch Dermatol. 2007;143(3):309 " 313.66 Kwok CS, Holland R, Gibbs S. Efficacy of topical treatments for cutaneous warts: a meta-analysis and pooled analysis of randomized controlled trials. Br J Dermatol. 2011;165(2):233 " 246.77 Ohtsuki A, Hasegawa T, Hirasawa Y, et al. Photodynamic therapy using light-emitting diodes for the treatment of viral warts. J Dermatol. 2009;36(10):525 " 528.
ADDITIONAL READING
- Dasher DA, Burkhart CN, Morrell DS. Immunotherapy for childhood warts. Pediatr Ann. 2009;38(7):373 " 379.
- Simonart T, de Maertelaer V. Systemic treatments for cutaneous warts: a systematic review. J Dermatolog Treat. 2012;23(1):72 " 77.
CODES
ICD10
- B07.9 Viral wart, unspecified
- B07.0 Plantar wart
- A63.0 Anogenital (venereal) warts
- B07.8 Other viral warts
ICD9
- 078.10 Viral warts, unspecified
- 078.12 Plantar wart
- 078.11 Condyloma acuminatum
- 078.19 Other specified viral warts
SNOMED
- 57019003 Verruca vulgaris (disorder)
- 63440008 Verruca plantaris (disorder)
- 240542006 Anogenital warts (disorder)
- 402908003 oral wart (disorder)
- 19138001 epidermodysplasia verruciformis (disorder)
- 240539000 Plane wart (disorder)
- 266113007 Genital warts (disorder)
CLINICAL PEARLS
- No single therapy for warts is uniformly effective or superior; thus, treatment involves a certain amount of trial and error.
- Because most warts in children tend to regress spontaneously within 2 years, benign neglect is often a prudent option.
- Conservative, nonscarring, least painful, least expensive treatments are preferred.
- Freezing and other destructive treatment modalities do not kill the virus but merely destroy the cells that harbor HPV.