WART (VERRUCA VULGARIS)

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

A typical patient is a healthy 14-year-old girl who competes on a local swim team. After each practice, she washes off in one of the public showers, which are small and do not meet adequate sanitary standards. Recently, she noticed the appearance of a flesh-colored hyperkeratotic papule on her right hand. The papule measured ~8 mm in diameter and was sprinkled with red dots, and its surface was rough and corrugated. Although it did not hurt or result in any symptoms, the girl nonetheless told her mother about it, who took her to a dermatologist to be evaluated.

• Scarring
• Pain
• Recurrence

• Approximately 2/3 of warts spontaneously regress within 2 years, but those who lack the ability to mount an adequate immune response may not resolve as easily.²
• Despite the variety of treatments available for verruca vulgaris, none are considered very effective. No single modality has been shown to be 100% capable of achieving complete remission, and recurrences are common with all interventions. There is also a lack of large, high-quality randomized-controlled trials available to inform clinical practice.^2,3,6
  • Salicylic acid has been associated with cure rates of ~50-70%.³
  • Higher remission rates have generally been reported with combined therapy, the most common approach being cryotherapy plus salicylic acid.²

• Diagnosis of verruca vulgaris is made primarily through the skin examination.³
• If a nail is involved, the lesion will likely involve the periungual or subungual regions.¹
• Hyperkeratotic papule or nodule
  • Flesh-colored 
  • Size ranges from 1 mm to >1 cm
  • Sprinkled with black or red dots (due to thrombosed capillaries)
  • The surface is rough and irregular
  • May occur individually, in groups, or in a linear fashion
• Warts can occur on any epidermal surface—including mucosal surfaces—but verruca vulgaris are most commonly seen on the hands and fingers, and may involve the nails.
• Most warts do not cause symptoms, but they do result in cosmetic disfigurement and cause localized pain in rare cases.
• Although warts are generally benign, there have been reports in which they may become malignant and develop into a verrucous carcinoma. This is a slow-growing, well-differentiated squamous cell malignancy that usually occurs on the plantar surface and is often mistaken for a common wart.³
• Autoinoculation, which is common with digital warts, often presents a therapeutic challenge due to their resistant and recurrent nature.²
• Biopsy may be performed if there is doubt regarding the diagnosis or suspicion of carcinoma.  Histopathologic features of verruca vulgaris include acanthosis, digitated epidermal hyperplasia, papillomatosis, compact orthokeratosis, hypergranulosis, tortuous capillaries within the dermal papillae, and vertical tiers of parakeratotic cells.^1,3
• Southern blot hybridization and oolymerase chain reaction may also be useful diagnostic tools.³
• Biopsy is warranted for subungual lesions that fail to respond to treatment, as the clinical presentation of subungual verruca vulgaris and subungual squamous cell carcinoma is similar.

New and Cited Articles

1. Marks JG, Miller JJ. Lookingbill and Marks’ Principles of Dermatology. Fifth Ed. London, New York: Saunders Elsevier; 2013.
2. Goldberg DJ, Beckford AN, Mourin A. Verruca vulgaris: novel treatment with a 1064 nm Nd:YAG laser. J Cosmet Laser Ther 2015;17(2):116-119.PMID: 25588038
3. Al Aboud AM, Nigam PK. Wart (Plantar, Verruca Vulgaris, Verrucae). In: StatPearls.Treasure Island (FL) 2019. PMID: 28613701
4. Kwok CS, Gibbs S, Bennett C, Holland R, Abbott R. Topical treatments for cutaneous warts. Cochrane Database Syst Rev 2012(9):CD001781.PMID: 22972052
5. Cha, S, Johnston, L, Natkunam, Y, et al. Treatment of verruca vulgaris with topical cidofovir in an immunocompromised patient: a case report and review of the literature. Transpl Infect Dis 2005;7(3-4):158-61.PMID: 16390407
6. Loo SK, Tang WY. Warts (non-genital). BMJ Clin Evid 2014;2014.pii:1710. PMID: 24921240
7. James WD, Berger TG, Elston DM. Andrews’ Diseases of the Skin.12^thEd. Philadelphia, PA. Elsevier, 2016.