Verruca vulgaris, also known as a wart, is a very common non-cancerous skin growth caused by infection with the human papillomavirus (HPV). These growths are harmless in most people and often go away on their own, but they can be bothersome, spread to other parts of the skin, or persist for years.
Verruca vulgaris can appear on many parts of the body. They are most often found on the hands and fingers, but they can also occur on the elbows, knees, face, scalp, and genital area.
They usually appear as small, rough, raised bumps that can be single or multiple. On the face, they may grow in a long, thin projection called a filiform wart. In some cases, a wart may form a cutaneous horn, which looks like a hard, cone-shaped growth.
Verruca vulgaris is very common, especially in children and teenagers. Studies show that up to 16% of children and about 3% of adults develop this condition at some point.
They are more common in people with weakened immune systems, such as patients who have had organ transplants or who are living with HIV. In these individuals, warts can be larger, more numerous, and harder to treat.
Verruca vulgaris is caused by infection with the human papillomavirus (HPV). There are many different types of HPV, and types HPV-1, HPV-2, and HPV-4 are most commonly found in verruca vulgaris.
HPV infects skin cells (keratinocytes) and causes them to grow abnormally, creating the thickened, rough surface of a wart. The virus is spread through direct contact with the skin or contaminated objects, such as shared towels or grooming tools.
Doctors often diagnose verruca vulgaris based on their appearance and location. In cases where the diagnosis is uncertain, a small tissue sample may be removed in a procedure called a biopsy. A pathologist then examines the tissue under a microscope to confirm the diagnosis.
When viewed under the microscope, verruca vulgaris shows several characteristic changes in the skin:
Hyperkeratosis (thickened surface layer) makes the outer skin look rough and scaly.
Papillomatosis (uneven surface growth) creates the bumpy or warty appearance.
Elongated rete ridges (finger-like extensions of the epidermis) grow deeper into the underlying skin.
Parakeratosis (retained nuclei in the surface layer) often appears as thin vertical columns above the ridges.
Hypergranulosis (thickened granular layer) is seen with coarse keratohyalin granules.
Koilocytes (virus-infected cells with hollow centers) may be present in the upper layers of the skin.
Dilated capillaries (enlarged blood vessels) in the papillary dermis sit just below the surface and explain why warts may bleed when scraped or cut.
These microscopic changes are important because they help pathologists distinguish verruca vulgaris from other non-cancerous growths that may look similar, such as seborrheic keratosis.
In most people, verruca vulgaris are harmless and will eventually regress on their own, especially in children. However, keep in mind:
Verruca vulgaris can last for years in some patients, especially those with weak immune systems.
Very rarely, verruca vulgaris can develop precancerous changes ( called squamous dysplasia) or progress to squamous cell carcinoma. This is more likely in people who are immunosuppressed.
Because of this, verruca vulgaris that are unusually large, rapidly growing, or resistant to treatment may be biopsied to rule out other conditions.
The outlook is excellent. Most verruca vulgaris are benign and self-limiting:
Many regress naturally within months to a few years.
Warts in immunosuppressed patients are more likely to persist or recur.
Treatment options (such as cryotherapy, salicylic acid, laser therapy, or immunotherapy creams) are often used if warts are painful, cosmetically bothersome, or persistent.
Should I be tested for underlying conditions such as high-risk HPV or immune problems?
What treatment options are available if the wart does not go away on its own?
Is there any risk of this wart turning into cancer?