ABSTRACT
It may occur associated with any type of eczema—mainly atopic dermatitis, allergic or irritant contact dermatitis. A good anamnesis is mandatory for the diagnosis. The history of exposure to an allergen, such as dichromate, nickel, cobalt, fragrance mix, epoxy resin, thiuram mix, paraphenylenediamine, and formaldehyde, is very common in cases of allergic contact dermatitis. Alkalis, acids, soaps, solvents, and abrasives are often reported in cases of irritant contact dermatitis. Clinical features depend on the area of nail unit involved. When the inflammatory infiltrate involves the nail matrix, nail pitting, trachyonichia, longitudinal ridges, transverse grooves, Beau's lines, and onycomadesis are often observed. Chromonychia, onycholysis, and splinter hemorrhages are due to bed involvement, while paronychia, pulpitis, fissuring, erythema, scales, and loss of cuticles are typical of periungual tissues involvement ( Figures 8.1 and 8.2 ).
