ABSTRACT
The pattern of separation of the plate from the nail bed takes many forms. Sometimes it resembles closely the damage from a splinter under the nail, the detachment extending proximally along a convex line, giving the appearance of a half-moon. When the process reaches the matrix, onycholysis becomes complete. Involvement of the lateral edge of the nail plate alone is less common. In certain cases the free edge rises up like a hood, or coils upon itself like a roll of paper. Onycholysis creates a subungual space which gathers dirt and keratinous debris; the greyish-white colour is due to the presence of air under the nail but the colour may vary from yellow to brown, depending on the aetiology. This area is sometimes malodorous.
