by Jason Wasserman MD PhD FRCPC
March 25, 2023
Verruca vulgaris is a non-cancerous growth caused by infection with human papillomavirus (HPV). The growth is made up of abnormal squamous cells and it is typically found on the skin although it can also be found on the lips or inside the mouth. People who are immune-suppressed are at increased risk for developing verruca vulgaris. Another name for verruca vulgaris is the common viral wart.
Verruca vulgaris is caused by human papillomavirus (HPV). There are many different types of HPV and most cases are caused by low-risk types such as types 1, 2, 4, and 11. These types are called low-risk because unlike high-risk types of HPV (such as 16 and 18), they rarely cause the cells to become cancerous.
Verruca vulgaris very rarely changes into cancer over time. In these cases, the patient typically has a weak immune system as a result of another condition such as HIV.
Verruca vulagris is typically caused by HPV types 1, 2, 4, 7, 26, 27, 28, and 29. Verruca vulgaris involving the genitals is often caused by HPV types 6 and 11.
The diagnosis of verruca vulgaris can be made after a small piece of the growth is removed in a procedure called a biopsy or after the entire growth is removed in a procedure called an excision. The tissue is then sent to a pathologist who examines it under the microscope.
When examined under the microscope, verruca vulgaris is made up of the same specialized squamous cells that are normally found on the surface of the skin and on the inner surface of the mouth. The squamous cells connect together to form long finger-like projections of tissue that stick out from the surface of the tissue. Pathologists describe these finger-like projections as papillary and the pattern of growth as exophytic which means growing outward. The surface is often covered by a thick layer of keratin. Abnormal-looking squamous cells with dark, irregular-shaped nuclei are often seen near the surface of the tissue. Pathologists call these cells koilocytes and they are a specific feature of HPV infection.
Your pathologist may not be able to see all of these microscopic features when only a small tissue sample is available for microscopic examination. In that case, your pathology report may describe the features as verrucous hyperplasia. This term is used to describe a group of abnormal growths that show features that overlap with verruca vulgaris.