Clinical Presentation of Warts
Warts usually present as common, palmoplantar, flat, or filiform in childhood, but variations by age are common (eFigure). The common and palmoplantar variants often are caused by HPV types 1 and 2.4,5 In infancy, vertically transmitted HPV infections can cause juvenile-onset respiratory papillomatosis or vertically transmitted condyloma. Juvenile-onset respiratory papillomatosis refers to upper respiratory papillomas that are difficult to eliminate and has been associated with exfoliated cervical cell testing with 18.1% (13/72) typed HPV-positive, which allows neonates to be exposed to HPV in the upper respiratory tract in utero.10
eFigure. Warts by types and locations. HPV indicates human papillomavirus; SCC, squamous cell carcinoma.
Vertically transmitted condyloma is a difficult topic. Much data supports the vertical transmission of condyloma as the leading cause of condyloma in small children; however, a reasonable amount of caution is needed in this patient population. In cases suspicious for sexual abuse as well as those presenting in children 4 years and older, formal household evaluation by a sexual abuse clinic and mandatory reporting is needed. Anywhere from 2.6% to 32% of cases of genital warts in children have been reported to be caused by sexual abuse.11-13 Therefore, most investigators have recommended careful review of the patient’s history and socioeconomic circumstances as well as a thorough physical examination. Mandatory reporting of suspected child sexual abuse is required in suspicious cases. Because HPV type 16 has been found in vertically transmitted cases, concern for long-term oncogenesis exists.11-13
Adolescents generally present with lesions on the hands and feet. Plantar warts often are caused by HPV types from the alpha genus. Subtypes noted in plantar warts include HPV types 1a, 2, 27, 57, and 65.14 By 15 years of age, genital HPV becomes a common adolescent infection, persisting into adulthood.15 When studied, genital HPV often is subclinical or latent and often is preventable through vaccination. High-risk oncogenic alpha-genus HPV types can immortalize human keratinocytes. When HPV types 11, 16, 18, and 31 are compared, HPV-18 has the highest oncogenic potential based on colony-stimulating potential.16 Vaccination with the 9-valent HPV vaccine is recommended in adolescence due to the concern for exposures to both low-potential (HPV types 6 and 11) and high-potential (HPV types 16 and 18) oncogenic HPV types. Data strongly support the benefit of 9-valent HPV vaccination in the prevention of sexually transmitted HPV in both males and females.17
Contagion of HPV is easy due to its excellent survival of fomites on surfaces, which generally is how warts are transferred in gym or pool settings where individuals who walk barefoot in changing rooms are almost twice as likely to contract plantar warts (odds ratio, 1.97 [95% CI, 1.39%-2.79%]).18 In another case series, walking barefoot, using a swimming pool, and having a household contact with warts were the leading risk factors for contraction of warts in children younger than 13 years.19 Children often transfer warts from site to site as well as to siblings and other close contacts. Skin-to-skin contact is responsible for sexual transmission of warts, and surface transmission occurs via fomites. Entry of the virus often occurs through small breaks in the skin. Other modes of transmission include orogenital.20