wart, circumscribed outgrowth of the skin caused by a filterable virus that is readily transmitted. Warts may appear anywhere on the skin but are most common on the hands. Sexually transmitted diseases and human papillomavirus produce warts in the genital area; these are often precancerous growths. Some warts disappear spontaneously; others persist for many years. However, there is also a tendency to develop new lesions. Warts are treated by surgical excision (sometimes by electrocautery), bloodless removal by freezing with liquid nitrogen, or repeated applications of ointments or creams. Those on the soles of the feet (plantar warts) are the most painful and most difficult to treat, since on pressure-bearing areas they may become depressed beneath the surface of the skin.