August 2007

This 9-year-old girl presented to the pediatric dermatology clinic with her mother who was concerned about a facial rash that started as a few “bumps” several months previously, but continued to spread.

What is your diagnosis?

Answer

The diagnosis is verrucae plana.

This girl has verrucae plana or flat warts. To date there are more than 100 different types of human papillomaviruses (HPV) that have been designated.

Flat warts are usually associated with HPV types 3 and 10 (and less commonly types 27, 28, and 49). Typically flat warts present as multiple smooth, skin-colored to slightly pink or brown flat top papules that measure 1 to 6 mm in diameter.

Verrucae plana may present as a single lesion or hundreds. Most commonly they present on the hands and face of children. In adults, there is significant association with shaving in both women and men.

Like many wart types, flat warts may be spread in a linear arrangement when traumatized, an effect known as Koebner’s phenomenon or the isomorphic phenomenon. On occasion, the warts may spread to such an extent that they appear more consistent with a single plaque rather than multiple isolated papules. A variety of therapies have been successful in treating verrucae plana. Everything from expectant therapy to laser has been implemented. Because of the affected facial area of our patient, scarring was a major concern.

We elected to use 5% imiquimod cream, an immunomodulating medication acting on toll-like receptor-7. Although this medication is not approved for non-genital warts, its success has been widely reported. The precise mechanism of its action has not been elucidated. The cream was applied to the area nightly without occlusion over an eight-week period. During therapy, a significant inflammatory response was noted; however, the lesions resolved completely without scarring by the end of the eight-week treatment period.

For more information:

• Paller AS, Mancini AJ, et al. Hurwitz clinical pediatric dermatology. Philadelphia; Saunders. 2006;406-411.
• Tyring SK, editor. Mucocutaneous manifestations of viral diseases. New York; Marcel Dekker, In.; 2002;258.
• Wolverton SE, editor. Comprehensive dermatologic drug therapy, Second Edition. Philadelphia; Saunders. 2007;575-576.