[Nail localization of dermatoses].

The nail unit may reflect a dermatological disease by its own. Actually, its involvement may account for the existence of a skin disease that never showed before (i.e. lichen planus). But since the nail apparatus has a limited repertoire of clinical expressions (hyperkeratosis, onycholysis, paronychia...), the diagnosis may be sometimes difficult even for the most trained physician. Nail involvement may be however an additional clue in the diagnosis of an atypical skin disease. In that case, it might help in the final correct diagnosis provided that the physician did not forget that clinical examination of the nails is part of a dermatological examination.