All warts are infection of the skin surface by the human papilloma viruses. Plane warts appear as fleshed-coloured or pigmented, very slightly raised, well-defined and flat-topped lumps.

They are particularly common on the face and hands. When they are small they are not very noticeable, but with time they will spread and become larger, and numerous of these seem to appear suddenly and can be cosmetically alarming. They can be freezed off with liquid nitrogen, burn off with an electric cautery or CO2 laser.