Verruca vulgaris. The common wart is a benign growth caused by localized infection with one of the many types of human papillomavirus. These small DNA viruses are part of the papovavirus group. Warts are especially common among children and adolescents and may occur on any mucocutaneous surface. The hands are a particularly frequent location. The typical wart is a roughsurfaced nodule that may be either lighter or darker than the surrounding skin.