A wart is a benign cutaneous neoplasm caused by a human papillomavirus (HPV) infection of the epithelial cells. Warts are extremely common, and many people will experience them in some form at least once in their lives. Over 150 subtypes of HPV have been identified, and transmission occurs directly through skin-to-skin contact or indirectly from contaminated inanimate objects when the skin’s protective barrier is compromised. Verruca vulgaris, or the common wart, is most commonly caused by HPV subtypes 1, 2, 4, 27, 57, and 63 (with HPV-2 being a common cause of hand warts), and is frequently seen on the hands, fingers, and around/underneath the fingernails.1-5
Pathophysiology
- Only a few of the >100 HPV subtypes can cause skin warts at selective anatomical sites, but the virus can be transferred to any part of the body with skin contact. Verruca vulgaris and other warts can be easily transmitted by either direct or indirect contact, especially when the normal epithelial barrier is disrupted.3
- The presence of HPV stimulates epidermal proliferation, which results in epidermal thickening and hyperkeratosis.1
- HPV usually only infects the epithelial layers of skin and is known to replicate in the upper level of the epithelium, but virus particles can also be found in the basal layer.3
- The use of communal showers, wet work with the hands, occupational handling of meat, and immunosuppression are all risk factors for verruca vulgaris.1,6
Related Anatomy
- Dermis
- Epidermis
- Epithelial cells
- Epithelial barrier
- Epidermal cells
- Keratinocytes
- Capillaries
Incidence and Related Conditions
- There is a lack of high-quality epidemiological data on warts, with most studies focusing on population subsets; however, it is generally agreed that they are uncommon in infancy, common in childhood, and then decline in prevalence from the second decade of life onwards.4
- Research suggests that warts affect ~10% of the population.3
- The prevalence of warts in children and young adults has been found to range from 5-30%, with a peak in prevalence occurring between ages 12-16.2,3
- Bowenoid papulosis
- Epidermodysplasia verruciformis
- Genital warts
- Heck’s disease
- Squamous cell carcinoma
- Verrucous carcinoma
Differential Diagnosis
- Actinic keratosis
- Bowenoid papulosis
- Callus
- Clavus
- Cutaneous horn
- Keratoacanthoma
- Lichen nitidus
- Lichen planus
- Molluscum contagiosum
- Perforating folliculitis
- Prurigo nodularis
- Seborrheic keratosis
- Squamous cell carcinoma