6 Verruca Vulgaris

6 Verruca Vulgaris (Common Warts)

CLINICAL APPLICATION QUESTIONS

A 7-year-old girl was seen by her pediatrician with a single wart on her right index finger. Her mother was told that treatment was unnecessary because the wart would resolve by itself. Six months later the child presents at your office with 30 warts over both hands, around and beneath several fingernails.

1. List the reasons why immediate treatment is indicated.

2. What preparation is required before active treatment begins?

3. What treatment approach is appropriate in this situation?

4. What will you tell the mother about prognosis and possible recurrence?

APPLICATION GUIDELINES

Onset

Common warts are caused by human papillomavirus infection; clinical lesions develop after a latent period of weeks to several months. They have a peak incidence in late childhood and adolescence and then the occurrence sharply declines. They may, how- ever, be found in all age groups. Usually patients will recall a single lesion, which is often interpreted at first as a splinter or thorn.

Evolution of Disease Process

The clinical course is variable. Some will develop only a few lesions over years, while others will be covered within a few months. Conventional wisdom is that given time all verrucae (VV) will spontaneously involute. Unfortunately this is not a universal occur- rence and in children, uncontrolled spread can lead to social disfigurement and infection of playmates and other family members. In one longitudinal study of the natural history of common warts, only 40% of patients were clear 2 years later.

Evolution of Skin Lesions

The initial lesion may be indolent for years but most often expands in size while satel- lite lesions emerge.

Provoking Factors

1. Natural sunlight or ultraviolet light in the UVA and UVB spectra.

2. VV is spread by close physical contact and fomites and is especially common in some occupations such as butchering, where chronic cuts and abrasions afford a

59

From: Current Clinical Practice: Dermatology Skills for Primary Care: An Illustrated Guide D.J. Trozak, D.J. Tennenhouse, and J.J. Russell © Humana Press, Totowa, NJ

60 Part II / Papular, Papulosquamous, Papulo-Vesicular Lesions portal of entry. Warts occur frequently on the soles of persons who go without footwear in locker rooms and public bath facilities.

3. In immunosuppressed patients, pregnancy, and persons in active stages of HIV disease, warts tend to be more aggressive and more refractory to treatment.

Self-Medication

Multiple proprietary wart medications are available at any pharmacy. The marginal efficacy of these products can be measured by the number that are on the shelf. On occa- sion, patients will have some success but in general most of these products are variations of keratolytics that have been in use since the early part of the last century. Self-treatment is a problem mainly when delay leads to widespread lesions or when applied to lesions that have been inappropriately diagnosed.

Supplemental Review From General History

In unusually widespread or therapeutically refractory lesions, obtain history for pos- sible sources of immunosuppression. Warts in the genital and perianal areas of small chil- dren have been reported in the literature as an indication of sexual abuse. In clinical studies where this has been investigated, the relationship to abuse has been unreliable. The practitioner should, however, be wary and look for other corroborating history or physical findings.

Dermatologic Physical Exam Primary Lesions

1. Tiny firm flesh-colored papules that interrupt skin lines or dermatoglyphic lines when on palms or soles (see Photo 6).

2. Filiform (threadlike) papules, especially on the eyelid and facial areas (see Photo 7).

Secondary Lesions

1. Raised dome-shaped papules with a grey-white scaling surface and black pinpoint blood vessels (see Photo 8).

2. Large nodules with multiple tightly grouped filiform papules, the tips composed of gray scale or tipped by black thrombosed vessels (see Photo 9).

3. Tightly clustered round papules often with minimal or no elevation (corymbiform pattern) frequently at sites of compression such as plantar surface of foot (see Photo 10).

Distribution

Microdistribution: None.

Macrodistribution:

1. Dorsum of hands, fingers, periungual tissue, and knees in children (see Fig. 4;

Photos 11,12).

2. Beard area and neck in young adult men (see Fig. 5; Photo 13).

3. Periungual warts are usually associated with nailbiting. This habit must be con- trolled for successful treatment of the warts.

4. Common warts may occur at virtually any site on the skin or mucous membranes.

Configuration

1. Grouped (see Photos 12,13).

2. Corymbiform (see Photo 10).

Indicated Supporting Diagnostic Data

1. Typical VV is clinically diagnostic. No supporting data are indicated.

2. On very rare occasions VV may be clinically indistinguishable from keratoacan- thoma or squamous cell carcinoma.

Skin biopsy: VV has characteristic histology. Skin biopsy will distinguish VV from other tumors and growths.

Figure 4: Macrodistribution of verrucous warts in children.

62 Part II / Papular, Papulosquamous, Papulo-Vesicular Lesions

Therapy Avoidance

Patients with active infection should avoid sharing of clothing, towels, footgear, sport- ing equipment, and tools with others. Untreated persons are a source of new infection or reinfection which is a very common occurrence among playmates and immediate family members.

Cryotherapy

Liquid nitrogen is at present the most effective treatment modality. In experienced hands it is safe and nonscarring; however, there is some discomfort involved. With proper preparation, children will usually tolerate treatment of a small number of lesions. The authors recommend application with large cotton swabs rather than a cryospray unit. The

Figure 5: Macrodistribution of verrucous warts in young adult men.

swabs offer greater control over the rate and depth of freeze with less risk of injury to deep structures. Severe peripheral motor and sensory nerve injuries and tendon damage have occurred with overly aggressive LN₂treatment. Areas of greatest risk are the ulnar nerve at the elbow, the digital sensory nerves, and the dorsal tendons of the hands. These injuries can be avoided by moving or elevating the skin away from the deep structure and con- trolling the depth of freeze. LN₂therapy must be repeated every 2 weeks until all warts are clear. Single applications are rarely curative. This is especially true with palmar and plantar verrucae.

Vesicants

Vesicants should be limited to the treatment of periungual and subungual warts.

Cantharidin 0.7% in flexible colloidin or a similar base is quite effective when applied for 48 hours and kept dry under plastic tape occlusion. After 48 hours, the tape should be soaked off, as the involved digit will be quite tender at that time. Stronger cantharidin preparations are available but should be applied very cautiously to avoid permanent nail injury. These products should be applied by the practitioner and are not recommended for home use. Treatment of warts on other locations with these agents is not recommended and may actually spread the lesions. As with cryotherapy, follow up and repeat treatment should be on a 2-week basis until the lesions are clinically resolved.

Curettage With or Without Fulguration

This modality has a lower overall cure rate than LN₂. In addition, it carries the disad- vantages of scarring and the need for local anesthesia. Today, curettage is generally reserved for the treatment of solitary warts that have proven resistant to other less or non- scarring techniques. This method of removal should never be used on a palm, sole, or the primary sensory area of a digit. Permanent, painful, disabling scarring may occur. Despite many early claims, laser therapy has about the same utility and disadvantages as curettage and fulguration. In addition, the equipment is costly to purchase and maintain. The authors have seen some very severe scarring as a result of inappropriate laser treatment of warts.

Keratolytics, Caustics, and Cytostatic Agents

These agents have been used singly or in myriad combinations for the treatment of common warts. Salicylic acid and lactic acid are the most commonly used keratolytics and can be compounded or purchased already made either by prescription or OTC. The plain keratolytics are quite safe, but only modestly effective. They must be used with gentle sur- face debridement and can be recommended for home use. Parents should be warned to return promptly if the warts are spreading. Combinations of keratolytics with vesicants (cantharidin) or cytostatics (podophyllin) produce products that can cause intense inflam- mation and limited tissue necrosis. These should be administered by the practitioner and carefully followed up. These preparations are most effective with periungual and subungual warts, and when used in other skin locations tend to cause annular spread of verrucae.

Caustics, such as mono-, di-, and trichloroacetic acid, are both keratolytic and viruci- dal. These acids produce almost immediate tissue coagulation and must be handled with extreme caution. They should be applied only to limited areas with either a flat toothpick or the tip of a broken cotton swab. The adjacent skin should be protected with a border of

64 Part II / Papular, Papulosquamous, Papulo-Vesicular Lesions petrolatum. If use is undertaken around the eye, be prepared to flush with water or sodium bicarbonate immediately in the event of contact with the eye. The action of these acids is self-limiting and adequately treated areas will turn an intense white color. Treatment is associated with a moderate amount of pain, that is usually transitory. Other caustics which are virucidal include formaldehyde and glutaraldehyde. Formaldehyde is sometimes for- mulated extemporaneously with the keratolytics and used under occlusion with daily debridement. Glutaraldehyde 10% buffered with sodium bicarbonate is particularly useful in the treatment of extensive plantar warts and for patients unable to tolerate cryotherapy.

The solution is applied morning and evening and the warts are lightly debrided by the patient with pumice stone or callus remover daily after showering. More vigorous debridement should be done in the office on a 2-week basis until VV is cured.

Patient compliance is easily monitored by the distinct orange-brown color produced at the treatment site. This side effect unfortunately limits the use of this regimen to the feet. Silver nitrate preparations are not recommended because of staining and toxicity.

Podophyllum resins are cytostatic agents that inhibit cell division in metaphase. They are used mainly in the treatment of moist warts located on mucous membrane areas and thin skin. They can cause serious and potentially fatal toxicity if ingested or if there is sub- stantial absorption from extensive application or use on areas of raw skin. In animal stud- ies, they are abortifacients and are contraindicated during pregnancy. They should be applied only by the treating practitioner. Patient application is not recommended.

Alternative Therapies

Topical immunotherapy, intralesional bleomycin, and the use of systemic retinoids all fall within the realm of the dermatologist and are either expensive, fraught with potentially significant complications, or still considered experimental. Intralesional and systemic interferon therapy using both natural and recombinant interferons has been reported, with markedly variable results in patients with condylomata. There is no body of evidence to support the use of these agents in the therapy of common warts. Interferon therapy is very expensive.

Conditions That May Simulate Verruca Vulgaris Plantar Calluses

The distinction between warts and plantar calluses is sometimes difficult and is impor- tant because the latter can be treated with keratolytics and debridement alone and do not require the more destructive therapies used on verrucae. The difference can be determined by paring the lesion down with a scalpel blade. Warts will show a single or sometimes multiple cores that interrupt normal skin lines. They also exhibit dark red or black speck- les, which are the thrombosed ends of the feeder vessels. Calloses show neither of these changes.

Basal Cell Carcinomas, Squamous Cell Carcinomas, and Keratoacanthoma

Large, keratotic VV that arise on sun exposed skin can simulate these nodular lesions.

The differentiation can usually be made with a skin biopsy. The specimen should be read by a dermatologist or dermatopathologist.

Verrucous Carcinoma of Skin (Epithelioma Cuniculatum), and Squamous Cell Carcinoma of the Nail Bed

These rare lesions can simulate VV both clinically and histologically. The distinction is important because both are capable of metastasis. More often they cause local invasion which necessitates amputation or deforming surgery. Verrucous carcinomas are sizable fungating lesions, often on the soles. These should be referred to a dermatologist for man- agement. Any subungual warty lesion that does not respond promptly to therapy should be referred to a dermatologist for evaluation. This is especially true in an adult patient or when there is a history of prior radiation exposure.

ANSWERS TO CLINICAL APPLICATION QUESTIONS

A 7-year-old girl was seen by her pediatrician with a single wart on her right index finger. Her mother was told that treatment was unnecessary because the wart would resolve by itself. Six months later the child presents at your office with 30 warts over both hands, around and beneath several fingernails.

1. List the reasons why immediate treatment is indicated.

Answer:

a. The warts are continuing to spread.

b. Some of the warts are split and tender and they interfere with manual activities.

c. Warts are contagious and the child is a source of infection for playmates and family members.

d. The child may become a social outcast due to the disfiguring appearance of these lesions.

2. What preparation is required before active treatment begins?

Answer: Before treatment begins, the mother and child must understand that treatment will require an indeterminate number of regular visits which must be followed through until the warts are gone. They must also understand there will be some discomfort.

3. What treatment approach is appropriate in this situation?

Answer: Combined therapy using cantharone under occlusion for the periungual and subungual warts, and cryotherapy with liquid nitrogen for the others.

4. What will you tell the mother about prognosis and possible recurrence?

Answer: With regular follow-up, the prognosis for cure is excellent. However, recurrences are possible and should be treated promptly.