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A 16-year-old girl presents with multiple flat lesions on her forehead (Figure 132-1). It started with just a few lesions but has spread over the past 3 months. She is diagnosed with flat warts and topical imiquimod is prescribed as the initial treatment.

Figure 132-1

Flat warts on a patient's forehead. (Courtesy of Richard P. Usatine, MD.)

Flat warts are characterized as flat or slightly elevated flesh-colored papules. They may be smooth or slightly hyperkeratotic. They range in size from 1 to 5 mm or more, and numbers range from a few to hundreds of lesions, which may become grouped or confluent. They occur most commonly on the face, hands, and shins. They may appear in a linear distribution as a result of scratching, shaving, or trauma (Koebner phenomenon) (Figure 132-2).

Figure 132-2

Flat warts just above the knee of a young woman. Probably spread by shaving. (Courtesy of Richard P. Usatine, MD.)

Plane warts, verruca plana, verruca plana juvenilis.

  • Flat warts (verruca plana) are most commonly found in children and young adults (Figures 132-1, 132-2, 132-3, 132-4, and 132-5).
  • Flat warts are the least common variety of wart, but are generally numerous on an individual.1
  • Flat warts are usually caused by human papillomavirus (HPV) types 3, 10, 28, and 29.2

Figure 132-3

Flat warts on the neck of an HIV-positive man. The warts have been spread by shaving. Cryotherapy and imiquimod were not successful but intralesional Candida antigen injections cleared all the warts. (Courtesy of Richard P. Usatine, MD.)

Figure 132-4

Close-up of a flat wart. Note typical small, flat-topped papule. (Courtesy of Richard P. Usatine, MD.)

Figure 132-5

Flat warts on the upper lip and nose of a young girl. (Courtesy of Richard P. Usatine, MD.)

  • Like all warts, flat warts are caused by HPV.2
  • Flat warts may spread in a linear pattern secondary to spread by scratching or trauma, such as shaving.
  • Flat warts present a special treatment problem because they persist for a long time, they are generally located in cosmetically important areas, and they are resistant to therapy.

Clinical Features

  • Multiple small, flat-topped papules that may be pink, light brown, ...

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