ABSTRACT
Onycholysis means separation of the nail plate from the underlying nail bed due to disruption of the onychocorneal band. It generally starts at the distal free margin of the nail plate and progresses proximally. Less often, it happens the other way around. Onycholysis is easily diagnosed clinically as a whitish appearance of the detached plate due to the light reflecting through it. Dermoscopy is extremely helpful to differentiate traumatic onycholysis from onycholysis due to other causes, mainly onychomycosis, and psoriasis. In traumatic onycholysis, the line of detachment is linear, regular and smooth, and surrounded by a normally pale pink-bed, without hyperkeratosis. In psoriasis the margin is slightly dented with orange-yellow border that corresponds to the clinical erythematous borders surrounding the distal edge of the detached nail plate. In onychomycoses, onycholysis has a ragged border due to the striped shapes of fungi invasion ( Figures 3.1–3.4 ).
