Periungual warts are found around the nails and cuticles of one's fingers and toes. They cause the skin to peel and often appear rough and irregular in shape. Some are very small, less than 1 mm in diameter. Others can spread over the entire nail and digit. Like all warts, they are caused by the human papillomavirus, or HPV. As such, they are tremendously resilient little buggers, highly contagious and not very socially popular.
Just like other garden-variety warts, such as plantar warts, treatment usually involves cryotherapy, a freezing process that kills the infected skin cells and, in turn, the virus. Other options include salycilic acid, prescription drugs, or even laser removal by your local dermatologist. Unlike other warts, however, periungual warts are particularly difficult to remove. They can cause permanent damage to the nail structure and are often very painful.
To protect your hands and feet from periungual warts, wash the skin on a regular basis--particularly after direct contact with infected persons or communal areas such as dorm showers or swimming pool decks. The skin is especially vulnerable to infection where it has been broken by abrasion or friction, so if you're a compulsive nail-biter or cuticle trimmer, beware!