Warts – Diagnosis, Symptoms and Treatment

What are Cutaneous Warts?

Cutaneous warts are skin lesions that appear as raised, flesh-colored papules commonly located on the hands or soles of the feet.  These papules often become rough and scaly (keratinized) and occasionally cause pain and discomfort.  Cutaneous warts are caused by the human papillomavirus (HPV) – plantar warts are typically caused by HPV type 1. The virus is transmitted by skin-to-skin contact as it enters microabrasions in the skin and mucous membranes.

Most children with competent immune systems will experience resolution within a couple of years.  However, adults often have a more prolonged course that often takes at least several years to resolve.  There are various treatment options available for symptomatic patients or those who desire cosmetic removal.  Due to this condition's importance, patients must understand its causes, symptoms, and treatment.

What causes Cutaneous Warts?

Cutaneous warts are caused by human papillomavirus infection.  There are almost 200 different types of this virus, and each type has a preference for a particular body part.  HPV type 1 typically causes infections in the feet' plantar aspect, whereas types 6 and 11 infect the anogenital region.  The virus enters the skin and mucous membranes through microabrasions.  The incubation period is about 2-6 months.

Infection with these viruses can eventually result in the formation of several variations – these include common warts (verruca vulgaris), plantar warts (verruca plantaris), and flat warts (verruca plana).  About 2/3rds of children have spontaneous resolution within 2 years. However, wart recurrence is common.  Adults typically have a prolonged course, taking several years, if not longer, for some warts to self-resolve.  Remission is most likely to occur in individuals with intact cellular immune systems.

How common are Cutaneous Warts?

They are exceedingly common in the United States and often initially evaluated in the primary care clinic.  Severe or atypical cases may require referral to a dermatology specialist, mainly if first-line measures are unsuccessful.

Cutaneous warts affect about 7%-12% of the population.  The prevalence is higher in school-age children, occurring in approximately 10-20% of this population.  They may affect any age-group but typically peak in incidence around age 12-16.  Immunosuppressed individuals and meat handlers are also at increased risk for the condition.

Signs and Symptoms

They usually appear as flesh-colored, raised lesions (papules) that can be keratotic (rough and scaly).  These lesions may cause discomfort or pain.  They are typically millimeters in size, although large warts up to a centimeter or more in diameter can be seen.

Diagnosis

Cutaneous warts are diagnosed clinically based on the appearance and distribution of the skin lesion.  Occasionally, when the diagnosis is uncertain, your doctor will use a scalpel to scrape skin debris off of the wart and evaluate for the presence of black dots.  These black dots represent thrombosed (clotted) small blood vessels, which is a highly characteristic finding.

Sometimes a dermatologist will use a scope (dermatoscope) to view the skin lesion under high magnification.  Alternatively, your doctor may recommend a shave biopsy to confirm the diagnosis, although this is rarely necessary definitively.

Wart Treatment

The majority of warts are self-limited and resolve on their own.  As a result, you may not necessarily require treatment.  Individuals with pain or cosmetic concerns or those with a history of immunosuppression (e.g., HIV/AIDS) can benefit from therapy.  Prolonged treatments are usually necessary at home or the clinic – these often lead to inconsistent results.  Some individuals improve, while a fair share of individuals experience treatment failure or recurrence of the wart.

The first-line treatment of common or plantar warts is topical salicylic acid or cryotherapy.  Cryotherapy is a freezing treatment that is performed in the office with a liquid nitrogen spray.  Some individuals experience pain and hypopigmentation with cryotherapy. Therefore, these side effects should be considered when deciding on treatment options.  Cryotherapy is generally avoided in young children for this reason but is often used in adolescents and adults.

Patients with severe warts or those that have refractory symptoms may benefit from the use of one of the following agents:

•         Topical immunotherapy with contact allergens
•         Intralesional Bleomycin
•         Topical or intralesional Efudex (5-fluorouracil)

Flat warts are typically managed with cryotherapy or one of the following topical agents:

•         Renova (Tretinoin)
•       Aldara (Imiquimod)
•       Efudex (5-fluorouracil)

References:

1. Hursthouse MW. A controlled trial on the use of topical 5-fluorouracil on viral warts. Br J Dermatol 1975; 92:93. 
2. Sterling JC, Gibbs S, Haque Hussain SS, et al. British Association of Dermatologists' guidelines for the management of cutaneous warts 2014. Br J Dermatol 2014; 171:696. - https://www.ncbi.nlm.nih.gov/pubmed/25273231
3. Kwok CS, Gibbs S, Bennett C, et al. Topical treatments for cutaneous warts. Cochrane Database Syst Rev 2012; :CD001781. - https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD001781.pub3/abstract