Warts are an infection of the epidermis. They stimulate the formation of surface projections which when viewed with magnification show a mosaic pattern. Each of the surface projections contains a black or red dot. There is a central vessel that can be found in the surface of all projections. This is a valuable diagnostic sign. It can be demonstrated by paring the surface with a 15 surgical blade.
Warts appear as discrete papules or in clusters. A cluster of warts is called a mosaic wart. These are especially difficult to treat. They are a common presentation on the plantar surface of the foot.
Warts may also occur between the toes and may cause discomfort.
Warts on the back of the hand may be flat. They are called flat warts and are very resistant to conventional therapy. They may last for years. These special forms may also be found on the face and lower legs.